Well Mike, I only see maybe one foam core every couple of years so I don't have a lot of them under my belt as a builder. In my case I wouldn't bother with one either. I have used those cool vacuum storage bags to sheet smaller planes with and thought they worked pretty well. With the few foam cores I see these days I agree with you, it isn't cost effective and I have never gotten any loose sheeting using weights. If I was cutting my own foam cores for all my building then I would make a vacuum system, they are slick but for the normal kit builder it would be pretty silly to go to the trouble of making up a system. I may have a nice old Byron 60 size Sukhoi with the glass fuse and foam wings on the board this year? As nice as this plane is I still will be using bags of lead shot. I have seen a photo of Speeds system {I think} and it is great, Wish he lived in the area, it would be a great borrow!!