This is the 8mm rod version with NEMA17 motors, T5 belts and an acrylic frame. The latest version uses an aluminium composite DiBond frame and is available as a full kit.
The source files and STLs for this and other sizes are on Github here: https://github.com/nophead/Mendel90. There are also bills of materials for each sub assembly, so you can see which parts go where.
Instructions for this version are in the RepRap wiki. The DiBond version has a detailed build manual here: https://github.com/nophead/Mendel90/blob/master/dibond/manual/Mendel90_Dibond.pdf
The base sheet is designed to be 10mm acrylic and the rest of the frame 6mm.
and one of all the other STL files.
Vitamins.txt lists all the other mechanical parts.