If only a few cases are needed for personal use,
then DIY ingenuity will provide. Several things spring to
mind
1) Cut from 1/8" sheet acrylic or
polyethlene in 2 superglued halves. Glue or screw. Wood is
possible.
2)Make a modelling plaster mould of a vfx cart. Cut
into halves. Hand carve plaster buttresses for screws to be drilled
later. Use fibreglass matt and resin to form
the casings in the mould.