Thread M3x6 bolts into the bottoms of the two posts (the bottom of the post has a through hole in the sides).
Attach one post to each of the short side beams, by sliding the head of the bolt into the top groove of the beam. Note how the bolt is tightened by inserting the wrench through the wrench access hole.
Insert 3 hex M3 nuts into the top grooves of the short side beams.
Attach the second posts to the beams.
Using M3x20mm bolts (and a washer) attach the back long beam to the post & beam sub-assemblies (via the hex nuts inserted above). Note: Attach the long beams with the holes for the standoffs visible from the top) and press the beam against the sides of the posts.
Attach the front and middle beams.
The spacing of the long support beams is 73mm:
Re-enforce the connections of the four posts to the tray by securing them to the side of the motherboard support beams via M3x20mm bolts, washer and hex nuts.
Note that the area where the PSU is mounted requires inserting two hex nuts into the side of the motherboard support beam prior to re-enforcing the corner post.
Attach the black plastic PSU tabs to the frame via a M3x8 bolt and washer.
Using M3x6 bolts and M3 hex nuts, attach the 4 small rubber bumpers (feet) to the bottom of the tray.
Using M3x20m bolts, loosely attach the 8 motherboard spacers to the tray (tighten after the motherboard is attached)
Load 8 M4 nuts into the top groove of the GPU support beam and start 4 M3x14 bolts with washers and square nuts.
Attach the GPU beam to the back posts by sliding the square nuts into the groves in the sides of the posts.
Using M3x20 bolts, washer and square nuts attach the GPU support beam.
The PSUs are attached using #6-32 5/16-inch long bolts and washers.
GPUs are attached to the tray via M4x6 Phillips-head bolts
Optional HD/SSD beams
The optional HD/SSD beams are attached to the tray with a M3x6mm bolt and nut.
Stacking connectors (threaded dowels) are threaded into the tops of the bottom tray’s posts. The top tray is attached to the dowels with M3x8mm bolts and square nuts. Note how the bolt goes through the access hole on the side of the beam, pressing against the threaded dowel.
Deep Mining Tray
Note that the two posts that support the GPU beam are attached to the side of a motherboard support beam (via M3x20mm bolts, washers and square nuts).