Reproducing Legacy Parts | 3D Printed Tooling and Resin Casting

Sometimes original replacement parts can’t be obtained and 3D printed parts may not be strong enough or too expensive to produce in volume.

This is one case where 3D printed tooling and urethane castings can help bridge the gap between the limitations of 3D printing and the design intent of the part.

The following is a brief 7 step guide showing the reproduction of a legacy part from start to finish using 3D printing, soft tooling, and casting.

Step 1: Create a CAD file of the original part that is to be reproduced.

Original Part

CAD Model


Step 2: Print the part which will become the master that the mold is then created from.

Printed Part


Step 3: Remove supports, blemishes from the surface, and prepare the master part to create the mold.

Finished Master Part


Step 4: Create a form around the master part with silicone rubber.

Mold Form


Step 5: Mix 2 part silicone and pour into the mold form and let cure.


Step 6: Separate the mold from the master part. Then use the mold to cast the new part.

Using Mold to Cast a Part


Step 7: Remove cast part from the mold and remove flashing/finish part as required.

Finished Part (Left) Next to Original Part (Right)


Designing Supports Into Part Geometry

There are several considerations when designing parts for Additive Manufacturing (AM). In many cases, AM has unique design considerations that differ greatly from standard design conventions typically seen in parts that are manufactured with subtractive machining processes.

One major consideration in AM part design involves overhangs and how each layer builds up as the part prints. Ideally each layer would build on top of itself which negates the requirement for support material; however, this is not always practical for some parts.

Consider a part with a flange like the one pictured below. Printed in this orientation there is a large overhang created by the flange that would require a significant amount of support material underneath it. Not only does this consume additional resources but also creates a significant amount of post-processing work after the part is manufactured.

By designing supports into the part, the need for extra support material is negated. This support material would have to span the entire distance between the build platform to the underside of the overhanging flange. The integrated supports build with the part and allow each layer to stack on top of each other neatly.

An added advantage in regards to integrated supports in this particular design is the added strength that is achieved at the intersection where the underside of the flange meets the body of the part. This sharp transition and relatively thin feature can be prone to breaking under high stress. With the integrated supports, the relatively weak flange transition area is strengthened.

This is only one example of designing for 3D printing; however, this subject is far deeper than can be covered in just a short blog post. Be sure to read our other blog post and feel free to contact us here or on social media with any questions.

Injection Mold Prototyping with SLA

Stereolithography or SLA is one of the most accurate printing processes in use today and has been around for nearly 30 years.

SLA additive manufacturing (AM) has become a go-to method for prototypes that require high detail and accuracy. The superior resolution of SLA makes this printing process ideal for replicating the surface finish of injection molded parts.

For these reasons, SLA has become an industry standard for prototyping parts prior to moving forward with costly injection mold making and part production.

The accuracy and appearance of SLA prints allow for an accurate representation of individual parts and also allows an engineer or designer to do a final check of assemblies comprised of injection molded parts to ensure proper fitment and operation.

Prototyping injection molded parts with SLA also helps to avert excessive costs in the design iteration process. Instead of manufacturing costly molds for producing only a limited number of parts in order to verify a design it is simple and cost efficient to print the part instead.

In some cases when the part is to be molded from a low-temperature thermoplastic this prototyping method can be reversed and a mold to make the finished part is printed using SLA.

Furthermore, SLA AM allows our customers to bring their product to market much faster than would be practical with traditional injection molded part manufacturing methods.

Although SLA can be the best method for prototyping injection molded parts it does have some drawbacks primarily with material strength and long-term durability. For these reasons, SLA is not ideal for prototypes that will see regular and hard use.

It is important to note that SLA materials are simulants meaning they have been engineered to perform similarly to actual thermoplastics like ABS for example.

These materials are an epoxy resin that is photoactivated. As a result, the materials are generally less durable than actual thermoplastics and will continue to activate when exposed to UV light. Because of this SLA parts are not ideal for outdoor use.

Injection mold prototyping is just one use case for SLA AM and this short article was just a brief overview. If you would like more information on SLA printing or see examples of printed parts click here.

Anatomy of a Printed Brick

Who says 3D printing to specific tolerances can’t be fun? Take a look at our take on the traditional LEGO brick.

I have designed a brick for 3D printing on our SLA printers and used some creative freedom along the way.

First of all, the critical dimensions of the brick and mating surface clearances were reverse engineered from an existing brick, then modified to our taste allowing for an interference fit. I wanted to test the printers accuracy and resolution as well. I decided it should be feasible to maintain a tolerance of +/- 0.005 in (+/- 0.127 mm) given the printers capability.

Before we jump into the bulk of this post I should mention that the CAD files for this brick can be viewed and downloaded on my GrabCAD profile.

Fortunately, SLA is one of the most accurate printing processes so there weren’t too many constraints to consider when designing the brick other than minimum wall thickness and overhangs for the intended orientation on the build platform.

As for the modifications from the original brick design, I removed the supports that extend from the inner center column to the 2 long outside walls and added supports connecting the 3 columns together. This was not completely necessary but it does provide some added strength to the thin columns and some support for the intended build platform orientation.

Bottom of brick with center connected columns and fillets.

I also gave generous fillets around the base of the columns for added strength and on all the corners for a more professional and finished look.

Fillets on outside of brick and small logo features.

The printer allows for a minimum feature height or thickness of  0.157 in (0.40 mm) which was taken into account for the logo and letters on each post.

The bricks were printed on a slight angle at a layer height of 50 microns to maximize the resolution and detail that the printer could reproduce. This also enables us to maintain uniform dimensional accuracy as well.

Printed bricks on build platform.

After post-processing, the newly designed bricks interface well with a standard LEGO brick or with more of our custom designed bricks.

Fit between a standard LEGO brick and our custom brick.

Just having fun














After printing we found that all dimensions were well within limits and only varied by +/- 0.002 in (+/- 0.0508 mm).


I’d say that is a success. Now I’m going to go and play with my super cool bricks.

3D Printing Complex Parts

3D Printing is still considered an emerging technology with many advancements still on the horizon; however, 3D printing has really shown its worth in several ways. One of which is producing lightweight structures that were not previously manufacturable or far too capital and labor intensive to manufacture with traditional methods.

On a rare occasion and between customer projects here at we like to embrace our inner nerd and print something interesting. This week it is the GE engine bracket designed by M Arie Kurniawan on GrabCAD  because we think this is the coolest thing since sliced bread as far as jet engine brackets are concerned.

The bracket was printed on one of our FDM printers in ABS. We use fully enclosed printers to keep a constant temperature which allows for large ABS prints without any warping. After minor post-processing, we primed and painted the model a color closely matching zinc chromate aircraft paint/primer just for fun (again the inner nerd is shining through).

By examining the front and back of the model you can see that the bracket features a complex design optimized for lightweight while still retaining the desired strength and safety factor. This is where 3D printing truly shines with its ability to reproduce complex geometry efficiently and at low cost.

Finally, the assembly was finished by bolting the bracket to a 3D printed ABS base with 3/8 in bolts for display.

The unmatched capability, material choice, and efficiency of 3D printing truly raises the bar for all types of manufacturing and brings new meaning to “the sky is the limit.” If you have a project in mind don’t hesitate to visit our website or contact us here.

7 Practical Uses for 3D Printing

3D printing is a versatile manufacturing process; however, many uses of 3D printing are still shrouded in mystery. The lightweight, low cost, and rapid prototyping/manufacturing aspects of 3D printing will soon replace subtractive manufacturing methods such as CNC machining.
This article details the 7 most practical uses for 3D printing and a few that may change the world. Who knows, after reading this you may get some ideas for your own project.

     1.Low Cost/Rapid Prototyping

3D printing allows for the rapid prototyping of parts in just a few hours whereas traditional methods may take several weeks. A part is designed in CAD software, printed, and held in hand in just a few hours. If necessary revisions can be made and a new prototype printed with minimal time lost.
With 3D printing also comes significantly lower prototyping costs when compared to traditional subtractive manufacturing methods. 3D printing uses less material and is capable of creating complex geometry that CNC machines can not.

     2.Short Run Production

Not ready to sink thousands of dollars into a full-blown production run or only need 10 to 100 parts? 3D printing is a great way to produce a number of parts in short order. Parts are also produced at low cost when compared to traditional methods.

     3.Legacy/Replacement Parts

Can’t find the parts you need? Just print them. Designing replacement parts or scanning old parts and 3D printing replacements is a great way to get the parts you need now or can’t find anywhere else.
Unique parts can be designed or scanned and then printed in a number of strong and durable materials to fulfill a variety of applications. Take a look at all of the functional materials offered by Tri Vector Printing on our services page.

     4.High Strength to Weight Ratio End Use Parts

3D printing methods lend themselves well to topology optimizing and light weighting parts while still maintaining the intended strength. Check out the GE engine bracket GrabCAD challenge winners for a prime example.
This is made possible by the nature of 3D printing itself. Printers can produce parts that are hollow with infill or have complex geometry that reduces material in key areas where it is not needed. This makes it possible to reproduce strong organic shapes that create a lightweight part while retaining the desired strength and safety factor.

     5.Educational Models

3D printing is a great way to make custom educational models that show the structure of molecules, assemblies to demonstrate the fit or movement of parts, and models of the human body. The sky is the limit.

     6.Affordable Prosthetics

3D printing has allowed for the manufacture of affordable and custom prosthetic limbs almost overnight for patients who can’t afford the traditional prosthetic device.
The remaining limb is often scanned and a socket can be printed to fit the patient exactly. This method not only speeds up the prosthetic build time but also alleviates the cost of custom prosthetics for patients whose insurance may not cover prosthetics.
Additionally, 3D printed prosthetics are easily replaced if damaged or outgrown. This is especially important for children who may need several prosthetics throughout their life as they grow.

     7.Jigs, Fixtures, and Tooling

3D printing allows for the rapid and cost-effective manufacture of custom jigs, fixtures, and tooling. Compared to traditional manufacturing methods 3D printing is especially useful for jigs, fixtures, and tooling that may be used only a few times before it is obsolete.
3D Printing also provides a freedom of design that is far superior to traditional methods which allows the designer to use less material while still maintain the utility and complex geometry of the jig or fixture.

The Super Awesome 3D Printing Dictionary





New to 3D printing or stumped by some of the terminology? We are here to help with a dictionary full of the most common and a few uncommon 3D printing definitions. Whether you are designing for 3D printing or just curious this database is sure to help.

For the sake of brevity we will disregard material abbreviations for now. That is the topic for a completely different post.


Additive manufacturing: Often used as a synonym for 3D printing. Additive manufacturing involves adhering several layers of material together to build a part as opposed to subtractive manufacturing which involves removing material from stock.


Bridge: A bridge is when the printer is required to build a layer over a gap without support material between two points.

Build Plate: The surface that the part is printed on.

Build Volume: The total area that the printer is capable of printing in.


CAD: CAD stands for computer aided design. CAD is a software that is used to design parts in 2D or 3D.

Curing: The hardening of photopolymers. Typically accomplished with exposure to UV light.


FDM: Fused Deposition Modeling is the process used by printers that extrude thermoplastic through a small nozzle.


G-Code: Commonly used name for the numerical control code used to drive a 3D printer.


Infill: A percentage value of how much the inside of a part is filled with material. 100% is solid whereas 10% infill is very light. Applicable to FDM printers.

Isotropic: A material that has the same properties in all directions.


Micron: A measurement of length. 1 micron is equal to 1000th of a millimeter. A human hair is approximately 17 microns.


Overhang: An Overhang occurs when a layer of material is only partially supported by the layer underneath it.


Photopolymer: A polymer that changes properties when exposed to UV light. Typically used in SLA machines.

Post Processing: The act of finishing a part after it has been printed. Usually involves removal of support material and smoothing the surface.


Resolution: Typically refers to the layer thickness or layer height of a print. The higher the resolution the smaller the thickness. Resolution is often expressed in microns or millimeters.


SLA: Stereolithography is the process used by printers that build parts from a vat of liquid resin with a UV laser.

.STL: This is the most common 3D file format for 3D printing and other 3D applications. STL files are compatible with most all 3D printers. The origins of the STL abbreviation are questionable.

Shell: A shell is the outer wall of a print. Applicable to FDM prints.

Support: Extra material that is used to hold up an overhang or bridge and is discarded in post processing.


Warping: The tendency for a part to deform or change shape. Common in some thermoplastics.