Thanks guys. Looks like the foam is the way to go.

Well, it's been 30 years since my dad and I built an elaborate 4x8 layout wnen I was a teenager. Now my son wants to build one. Thought we would start simple. All he wants is a figure 8 over and under. Any suggestions??  I've been out of this for a LONG time!! Any ideas or help would be greatly appreciated. Should I scratch build it or is there any train sets or track sets that anyone would recommend? Don't want to break the bank on our first build but don't want to go cheap either. Thanks in advance.