transfer the weight of the components to the top skin. think of a tray
that the electronics sit in, bonded to the underside of the top skin.
you can bond it to the bottom skin too, if you want, but the important
loading is to the top.
the inturrupted rib isn't helping much. a lighter rib right on either
side of the component tray will probably be better.
screws into the edge of MDF are pretty much useless.
don't notch the long ribs (the ones that turn the corner and bear the
weight of the top) very much. don't make them from MDF either. the
transverse ribs can float between the long ones. it will be convenient
for assembly to fasten them into a frame before applying the skin, but
not necessary for the strength of the finished article. try to either
limit yourself to fasteners that don't displace a lot of wood (like
finish nails) or have correct pilot holes for the screws you use.
shifting the notches (staggering the transverse ribs) is fine, and
will help avoid weak spots lining up with each other. better is to not
this assembly is similar to a hollow core door. in a door, the
function of the ribs is taken up by some lightweight, more-or-less
continuous material like foam or cardboard. you need to bear weight
against the panel, so you will need a thicker top skin and some ribs
running the long way. other than that, though, it can be a lot like a
hollow core door. the cross ribs can be replaced with shaped blocks of
foam, if you want. the bottom skin, the harder one to assemble, can be
thinner that the top. if you can, the cool way to make the ribs is to
either steam bend or laminate hardwood.