I managed to accomplish a few things again. The new front panel is made of 3mm thick plexiglass, the 130mm holes have been cut with a Dremel.
The plexiglass was painted with a matt black. The middle plate is a 2mm thick aluminium plate (the reservoir would have been too heavy for plexiglass, it would have bent).
With a countersink I cut six holes for the bulkhead coupling. You can find 10 holes on the sides of the plate (take a guess what the straw is for?). The middle has two holes for in- and output of the reservoir.
Again, the plate has been painted with a matt black.