It's not difficult to do. Definitely go for a single point light source though. Vacuum blanket isn't a must and it's probably the most difficult part of the build. We've built our own with a 1000w mh light from a grow shop and made a holder for it. No vacuum blanket, although I've got a javac pump and I was initially going to make one.
We just use a flat black rubber mat cut to size, with high density foam on top and 2 X 10kg weights for compression. We expose very good 55lpi halftones in around 80 seconds.