HI! I designed a semi-permanent modular workbench, its 18in wide, 18in deep, and 40in tall.
after some testing with a measuring tape and sitting in a variety of chairs, I calculated that 40in is a decent height while sitting and standing!as for the 18in depth, I figured its good as a shallow table, or if you stack 2 together itll be 3ft deep which is a great workspace!
the model comes with the bolts for the notches that are cutout on all 4 sides of each table, so that the bolts and washers can hold the tables together securely and at the same height, provided the floor is even.