Prepare Parts.
Print two of each part in the BOM. I used PLA printed with 10% fill density. sand or file the mounting holes for the pipe to give a good fit. They may be printed slightly too tight initially.

Cut your lengths of pipe to length. The 140mm piece can be any length greater than 130mm. The two uprights should be matched as close as you can get them.

Assembly.
Identify the bolts on your printrbot that line up with the holes in the printed parts for the four side arms. For one arm at a time, slightly over tighten these bolts then unscrew. use the same bolts to attach the printed arm. They should be just long enough to engage the captive nut. If they are too short, swap the bolts for 20 or 25mm M3 (some are spare in the 1405 kit). I needed to swap one bolt.

With all four bottom arms attached fit the uprights. Attach the top stand flush with the top of the pipe. Secure with zip ties or nut and bolt through the holes in each piece.

Spool rocks back and forth to take up the slack in the filament when printing.