The green/black/red rigid board with copper traces. The physical substrate every electronic device is built on.
How it looks
Real image: CORE3588, rendered by KiCad from our board file
CORE3588 as the fab delivers it: a bare board, 86.5 x 101 mm, four layers of copper inside, nothing soldered on yet. (KiCad render with all part models removed.)
1Copper tracks, seen as raised lines under the green coating.
2Rows of bare copper pads: the 100-pin socket for the computer module will be soldered here.