3D Printed Prototypes of Casting & Reloading Tools

3D Printed Prototypes of Casting & Reloading Tools

Thanks to advances in computer-assisted design software, as well as modern manufacturing technology, it’s now easier than ever to design and build high quality tools.  While it’s true that this has made things simpler and more accessible, the fact remains that prototyping costs continue to be a major concern for individuals and startups alike, often rendering a project prohibitively expensive to produce.

Fortunately, another recent technological development is helping to address this problem; 3D printing.  Most folks have at least seen or heard of 3D printing; an additive process that uses materials like PLA and ABS plastic to slowly build objects, layer by layer.  While much of the hype surrounding 3D printing has focused on finished products, it’s also a great way to prototype designs so that they can be interacted with and perfected in the real world.

In this article I’ll be discussing how I used 3D printing to build some rough prototypes of a couple tools I designed including an updated filler wad punch for shotshells, and a buckshot mould for casting #0000.  If you choose to watch the video above, I’ll apologize in advance for the 3D printing footage; the facility I used did not allow video cameras on premises, ironically they had no problem with me using a cell phone…


The process begins with a CAD application, in the video above, I used FreeCAD, an opensource application available to anyone.  Once the basic 3D model is completed, I typically take a quick look at it to ensure everything seems right before exporting it as an STL file.

Next I import the STL file into a slicer; this is an application that takes a 3D model and converts it into GCODE, the language used by a 3D printer to recreate the model, one thin layer at a time.  A number of options can be used here to fine tune the printing process, including detail, base style and how much to fill in solid areas.

The mould shown above is just a visual prototype vs a production model, so I opted to use very little fill in order to speed things up, and conserve printer filament.  Conversely the punch tool displayed was designed to actually cut material, so I opted to fill it in to ensure it was strong enough for that purpose.


With the GCODE file in hand we can now begin printing.  As you’ll see in the video above, it’s a painstaking process.  The part shown on the bottom of the punch (looks like a pink disk) is a temporary base added to the project to ensure it stays affixed to the printer, and doesn’t fall over or move during production.  Everything else is the actual part.

As the printer adds layer after layer of material, the punch and moulds slowly begin to take shape. Notice how in certain areas with an overhang, there are occasionally small defects. These are considerations you need to make as a designer when deciding how to orient the print job. In the future, I’ll place things so as to minimize this as much as possible.

Even before the printing is complete I can already see changes I’m going to need to make to the mould shown above.  The alignment pins are longer than I’d visualized, while the pour holes are too narrow.  This is where low cost prototyping really comes into play; instead of spending $300 to see there’s a problem, I’m able to recognize issues like these for a few bucks.

Printing time varies dramatically from project to project of course.  Large, detailed, or solid objects can take many hours to complete.  The punch shown about two hours, while the mould was over four.


With the completed printouts in hand, it’s time to head back home to clean them up and trial them.

Beginning with the punch, you’ll note that even the highest quality setting still yielded a somewhat rough finish.  The tiny grooves highlighted in the video are the individual layers as they were printed out.  As this tool has to be fitted to within a couple thousands of an inch to work properly, I’ll use a file to smooth it out, and clean up the base.  Likewise the cutting edge on the punch isn’t nearly sharp enough due to printers resolution limitations.  Once again, using a file I’ll sharpen this to a keener cutting edge.

Moving on to the mould, once again, the limitations of the printer are such that some cleanup is necessary.  In this case I’ll file the pins smooth, trim the flash around the pour holes, and clean up the ragged overhang of the handle channels.


With those modifications complete, the punch installs easily enough, and I’m ready to begin testing the new design. Although the plastic is fairly soft, if you look at the video above you’ll see it’s cutting much better than the previous punch style using materials like craft foam and cork.  This new punch is going to work great, and can finally go into finished production.

The mould is likewise ready for trialing.  After the cleanup, the handles fit well enough, and with a bit of coaxing the brass machine screws slot in just as nicely.  The blocks look and feel right, locking up well, and clearly small enough to work properly with bottom pour melting pots.  A couple small changes to the CAD file and this mould will be ready for production as well.


And that’s pretty much it for 3D printing prototypes.  For the price of a burger and fries, these two 3D models have provided me with a wealth of information on how my designs will function in the real world.  I now know the new punch design is ready to go, and what changes will have to be made to my mould to ensure it’s a success.

Share this:
Notify of
oldest most voted
Inline Feedbacks
View all comments