I just built this workbench with 2 layers of MDF glued together. I used a 1/2" spacer for the vices. So far I'm VERY happy with this workbench except for 1 thing: it's a little low. I followed some directions, but should have made it about 6 inches taller. Would have been a little easier to work at with a stool and it could double as an indeed table for my TS. Live & learn I guess. I've already gotten lots of use out of it.
Also, whenever I am doing anything that I think might damage the workbench, I throw. Piece of hardboard on it. Seems to protect very we'll when necessary.
"Measuring is the enemy of accuracy." Chris Schwartz