Continue #plotterbuild today, left side of pen rail: y axis belt/roller mount and X axis belt tensioner. Parts:

Pen rail assembly 
1x 5x12mm machine bolt
1x 5mm bore 20 tooth GT2 idler pulley 
Printed Tensioner housing
Printed tensioner and tensioner nut (not shown)
Printed left side y axis belt/roller mount 
2x 3x12mm machine bolts 
2x 3mm t nuts
2x 5x30mm machine bolts 
2x printed wheel bushings
2x mini roller wheels 
2x 5mm nylock nuts
https://cdn.masto.host/mastodonart/media_attachments/files/112/615/788/276/430/731/original/75a260e9802bdcfb.jpeg