Foam board is nice for building train layouts, since it’s lightweight and versatile. It’s easy to cut and shape into mountains and valleys and rivers. It’s also inexpensive. The problem is that screws won’t stick in it. So it’s tricky to fasten Lionel track to foam board. It’s difficult to fasten any other kind of track too.
Here are two ways to do it.
My favorite way is easily reversible. Use wire zip ties. Position the track on the board, then poke a hole through the board into the underside. Stick a wire zip tie down into the hole, leaving the square-shaped fastener visible. From the underside, attach a second tie to the first by zipping its fastener onto the length of the tie. Cinch the fastener tight enough that the track doesn’t fall off, but leave a little slack until you’ve finished laying track. Once you’re done laying track and adding ties and everything fits, come back around and cinch the fasteners tight.
To remove the track, just use a set of diagonal cutters to snip off the fastener holding the track in place.
Now you can ballast your track. Keep in mind once you ballast the track, you probably won’t be able to remove it and change it.
If your track doesn’t have holes big enough to accommodate zip ties, glue it down with polyurethane construction adhesive. Place some weight on the track until the adhesive sets up. Let it dry according to the instructions on the tube before you ballast the track.
That’s how you fasten model train track to foam board.