This is a custom loom my Dad made for me c.1991. The working length can be adjusted by moving the one upright and hook to another set of holes.
Over time, I’ve lost one of the combs and the hook on the end (left in the pics) has gotten bent, but these are both easily replaceable (almost any plastic comb and a standard cup hook).
Width: about 3″; Overall length: about 34″
Working length: adjusts to 6″, 12″, 16″, 20″, 24″, 26″, and 28″