I needed a bumper (base) for the ICSP circuit I made on EasyEDA so I designed this.
It has rounded outer corners and two notches along the inside to clamp the board down in the case so it won't move around.
Don't forget to allow for legs and solder when defining the height - for example FR4 is 1.6mm thick, but this needed almost 4mm due to some long legs on the headers.
Pro-tip: when ordering boards from JLCPCB, don't expect them to figure out that you wanted them to v-score the board even though you set 3 board outlines and printed dividing lines on the silkscreen.
Took about 35min to print.
Pro-tip: don't swap white and black filament without doing a "wash" print first or you end up with flecks of black in the white.