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Several people have looked at me with surprise when I say I am make my own prototypes in my basement. The decision was purely a matter of cost.

When I started researching how to turn a thought into a prototype, I learned there are charlatans willing to take your money for the promise of a CAD (Computer Aided Design) file and a working prototype. You likely get the file for the reasonable price promised, but then have to come up with a lot more cabbage to actually get the working prototype.  I got prototype bids, and could do the math pretty quickly:

4 sizes x 3 iterations (and it turns out I needed more) x cost per prototype = More money than I had for prototypes.

So, I just started researching on the internet, and ended up taking a free one-day class on making molds at Reynolds Advanced Materials. Reynolds, with locations in nine major cities, has done alright in the deal, as I have purchased almost all my materials from them. The process is best seen via this short YouTube video (1 minute 16 seconds):

Here are the steps I followed:

o Verify you have a viable product at an acceptable cost – topic of another blog post

o Design your prototype plan and estimate the cost

o Find a CAD designer – these are typically people with engineering degrees. I found Rob Miller at Loophole, Industrial Designer, who has an office in my town, Denver. I like working locally when possible.

o Purchase and assemble 3D printer



o Obtain CAD files from the designer – these may also called STEP files. My designer uses SolidWorks, a very common CAD program. For each size\iteration, I had 3 mold files, as I needed to print a three-part mold. The three parts were the core, the front and the back.

o Use the software that came with the 3D printer to convert the STEP files to .gcode files that are read by my Creality 3D printer. Put the converted files on a mini disk.

o Insert the mini disk into the 3D printer.

o Print each of the three parts of the mold in turn.

o Spray each part of the mold with release agent – this is critical. Without release agent, I practically destroy my mold getting the part out.

o Clamp the three parts of the mold together. My mold included a funnel at the top where the silicone is poured.

o Mix silicone, pour into mold. Wait for silicone to cure. The amount of cure time required is specified on the silicone packaging.

o De-mold the prototype. This means using all my strength to pry the mold apart.

o Trim excess silicone off the prototype.



Gem of Wisdom:  Be sure you know your prototype and manufacturing costs before moving forward with spending any money.  Don't spend money you can't afford to lose.

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