Updated on 8/8/2017
Added version of Controller - top and Controller - mount modified to fit 45 degree twist magnets,as per request :) In 2 versions: with and without the "stop bumps", as I don't have those magnets on hand to verify which feels better.
Twist release magnets can be found here:
http://catalog.polymagnet.com/1002305.html

While there are many existing variants of gun stocks available either for 3D printing, or purchase (on Etsy, eBay, etc.), I had some issues with the few ones I tried, thus I made my own version.

Is it better? How is it different from other designs?

There are few things I'd like to call out;

• this design is easier to print - may not look as cool as a version made to resemble Picatinny rail, but the print time is significantly shorter, there's no need to remove tricky supports, and the construction is very sturdy,
• can be printed on small bed size - including Monoprice Select Mini! (which is what
  I use :) just make sure you rotate the longest pieces [rail, stock a, stock b] and decrease the brim size to 6 lines),
• the stock is adjustable - the spacing between controllers, as well as controllers and arm support can be adjusted in 1.6" - 2.4" increments to make sure it fits you comfortable,
• the shoulder support part is lower than the rail, which makes sure it doesn't hit the headset during intense gaming sessions,
• multiple sizes of magnets are supported - if you have some, chances are they may fit - and if not, you can either buy the ones I used, or leave me a message with the exact dimensions of your magnets (diameter, height) and I'll make version for you :) [absolute max would probably be around is 20mm x 10mm],
• you can easily attach strap to have the accessory secured when not in use, or prevent it from falling when reloading in Onward while under fire ;) Just guide the strap through one of the unused holes in the rail,
• and, well, my design is tried :) I printed out a number of versions, improving parts in between, making sure the tolerances are correct and everything fits properly and stays strong. Some of the other available designs that I tried had issues with tolerances and wouldn't fit without manually trimming the parts after printing.

But you be the judge, and please let me know if you have any feedback :)

And most importantly, I hope you'll have fun using it!

Parts to print:

• 2 copies (one for each controller): Controller - bottom
• 2 copies (one for each controller): Controller - top - select the variant for your magnet size
• 2 copies (one for each controller): Controller - mount - select the variant for your magnet size
• 5 copies: Rail
• 1 copy: Stock - A
• 1 copy: Stock - B

Required for assembly:

• screw + nut, #8-32 x 1-1/2 in - quantity: 4
• screw + nut, #8-32 x 1-1/4 in - quantity: 6
• magnets - use neodymium, not ceramic disc (we need more strength than those can provide. Quantity depending on the size - see the "Controller - top" and "Controller - mount" part variants as reference (for a total of 12 or 14 magnets). The bigger the magnet (the stronger it is) - the better :)

Links to hardware (if you need to buy any):

• screws: http://www.homedepot.com/p/Everbilt-8-32-Machine-Screw-Kit-800994/204331402
• nuts and washers: http://www.homedepot.com/p/Everbilt-94-Piece-Stainless-Steel-Nut-and-Washer-Kit-803334/205949033
• magnets:
  • http://www.homedepot.com/p/MASTER-MAGNETICS-0-7-in-Neodymium-Rare-Earth-Magnet-Discs-3-per-Pack-07047HD/202526369
  • http://www.homedepot.com/p/MASTER-MAGNETICS-1-2-in-Neodymium-Rare-Earth-Magnet-Discs-6-per-Pack-07046HD/202526367?keyword=neodymium+6+per+pack
  • if you head to Home Depot, you'll find a selection of magnets in the aisle with machine screws and fasteners: http://imgur.com/QZAhJz9

I recommend magnets: 0.472 x 0.118 inch (12 mm x 3 mm).
They're available in Home Depot as well.

Hope you enjoy!

For other hobby projects, please visit my blog:
http://www.BogdanBerg.com/