Right after modelling the main parametrics of the frame, I’ve gone on to make it ready for 3D printing.
First, I have added screw holes in the bottom of the frame for attachment of a battery holder, and I slightly thickened the top of the walls on the long sides to allow room for embedded nuts for attachment of a lid.
Here’s the bottom:
I may not use all 8 screws, but I have put all the holes there in case I do need to.
For the top I have modelled in four hexagonal cavities for nuts to be embedded in, as you can see in this section analysis:(continued)