I would like to have pull-down work surfaces on all 3 of the middle niches (I would probably use 2 as desks but install 3 for symmetry). It is a perfect height for a work surface. I would put my electronics workstation in there. I think an 18" fold down work surface would be ideal (in addition to the 12" depth of the shelf). Above that (the niche is 62" total) would be french door style cabinets. The niches are about 35" wide so the doors would be nearly the same extension as the work surface. I would want to make sure the doors were removeable in case I wanted to work in multiple at the same time. I also like the coffered ceiling ideas.
Pull down work surface in a cabinet
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