2U Rack Mountable Raspberry Pi Holder for Raspberry Pi Super Computer

Here it is, the 2U rack mountable for 21 Raspberry Pi 3B+. This the rack that held the 1024 Raspberry Pi at CodeOne San Francisco 2019 in the Raspberry Pi Super Computer.

You will need the following:

1. (21) Tapered Heat-Set Inserts for Plastic, Brass, M2.5 x 0.45 mm Thread Size, 3.4 mm Installed Length, Packs of 100. I ordered 94180A321 from McMaster-Carr
2. (21) Button Head Hex Drive Screw, Passivated 18-8 Stainless Steel, M2.5 x 0.45 mm Thread, 5mm Long, Packs of 25. I ordered 92095A457 from McMaster-Carr
3. (4) 10-32 3/8in long screws with flat head. I ordered 91253A001 from McMaster-Carr
4. (1) 18" 80/20 Seris 15 .5in x 1in https://www.amazon.com/gp/product/B00IWZFPCS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
5. (21) Raspberry Pi
6. (21) 90 degree micro USB cables
7. (1) 24 port or larger switch
8. (1) 24 port or larger 5v USB power supply, for example: https://www.amazon.com/gp/product/B07MB12XZ4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
9. And various t