Does anyone have a box shape for a diminished scale so I can find it quicker on the fretboard?
My shape for diminished scales is a parallelogram, not a box. Box shapes are awkward for diminished scales because of the proximity of the notes. Here is a simple hand sketched diagram. This scale shows the starting notes for both whole/half and half/whole steps:
An easy fingering approach to this is 1-1 3 4 on each string ascending and the reverse descending. If one really wanted to do a more vertical box shaped diminished scale it would be 6 frets wide. This is easier, more practical and has a bit more range.
EDIT: Here is the more vertical box shape I mentioned earlier, just take out the yellow highlighted notes from the original and play the red ones instead. It involves playing 3 diagonal half step pairs in a row from the A to G strings and is harder to play: