Using a couple of pieces of scrap wood, 4 drawer slides and 2 dowels.

M3 - 8 bolts to attach the adapter to the drawer slides

M3 - 15 bolts with nuts to fasten the adjustable arm to the slotted elbow.

Used for supporting material as it extends past the Glowforge Pro slot so that the material does not cause the internal portion to rise. 

Lay model flat on bed with pins facing up. No support or skirts are needed.