Little support piece to add a bottom or deck plate to your 10" rack from @chris_337748. The holes have a 4mm diameter, so you are able to get heatinserts in or use m3 screws. If you want to install it, you have to turn the side panels to the outside (longer side is on the outside, like the picture).
If you use heat inserts, I would recommend to insert them from the other side. So If you want to screw it on the top, insert it from behind for a stronger connection.
The author remixed this model.