This thing is a parametric thrust bearing race cage generator. The parameters let you change ball bearing size, ball bearing spacing, ID/OD of the upper and lower sandwich washers, thickness of the cage, number of rows of ball bearings, addition of a compressed outside row, and finally the number of copies generated for a single output.Average cost < $0.75 per thrust bearing.These bb race cages can be either 3D printed or cut on a CNC router, mill, etc. If you use a 3D printer, you may want to determine the slop in your print by first printing a single race cage and taking the ID/OD bb measurements and updating the slop in the OpenSCAD file.To create a thrust bearing using this thing, you will also need 2 matched washers of the ID/OD appropriate for your application, a supply of ball bearings, and some tape.1) Determine the ID/OD of your bearing, any printer slop, ball bearing spacing and ball bearing diameter (I used 4.3 mm bb's from and air rifle). 2) Adjust the number of copies for your application. 3) Print or cut the generated model. 4) If 3D printing, use appropriate sized drill bits for any cleanup of the interior shaft hole and bb holes. I used a 3/8ths drill for my shaft clean up and a 3/16ths for my bb cleanup. 5) Lay 2 stips of tape face up on your work space. 6) Lay the first washer on top of the tape. Make sure not to block the center hole with tape. 7) Lay one of the printed race cages on the washer and fill bb holes with bb's. 8) Carefully place the 2nd washer on top of the bb's and gently wrap the ends of the tape over the top washer. Don't block the holes. 9) Place the thrust bearing in your application and firmly secure it in place. 10) Carefully cut the tape and remove with needle nose pliers. 11) RepeatFeatures: 1) option to have either a set number of bb's or autogenerated based on:Tips: Use typical metal crossman 4.3mm bb's for metal washers. Use airsoft bb's for metal or plastic washers Use fender washers for multiple rows of bb's.