My dark room sink was home made with half inch plywood (C-D grade of course) covered with a hand lay up fiberglass sheet and resin (tastefully dyed grey, of course). The bottom of the sink bowed up, which of course put the drain at the high point of the sink.....

The darkroom tables were originally nailed together and quite laughable. I was able to upgrade table construction by using "slotted angle iron" to make some hell for stout tables to hold the enlarger and the fiberglass sink.