the SSD PCB sits very nicely now. the heatsink model has a pad at the
bottom but it is not the case with the actual sink in use.
will remove it later.
the change also makes the base plate shorter, right about the size of
the display: will be splitting the box in two to allow printing within a max
circle area of 140mm diameter.
all are parameterized via the asmsheet which now includes
a calculation for an exploded view.
while there, added the missing display standoffs.
what's still missing is:
- SSD board
- heatsink top/bottom spacers
- outer case walls and mount holes