I am a newbie and am just getting round to using rolling stock etc I bought 43 (yes 43) years ago. I have seen layouts built on polystyrene foam baseboards and am attracted to it for ease of working and "tunnelling" options.
Has anyone built such a layout? If so would be interested in comment on "advice, tips, tricks and traps".

I'm building a door sized layout using a polystyrene base board. The actual baseboard is made out of very dense styrofoam ceiling board called Isoboard here, it is similar to the dense blue and pink insulation broad found in Europe and America. The scenery has been built out of the lighter more crumbly polystyrene that breaks down into beads. All the layers are stuck together with white wood glue.

I have used Woodland Scenics dark grey foam track bed. All the points are controlled by hand bar one which is operated by wire in tube.

I'm about half way through and so far everything has gone very well.

The actual baseboard is very rigid and rests on a smallish table, it's not likely to need any bracing.

I will try and post some pictures if I can remember how to do it, one thing I find very difficult to do is posting pictures to the forum  :'(

I am in the process of building an 'All Polystyrene' layout Construction Tools Link.

Although this is ostensibly constructed using Woodland Scenics products the first few posts should give you an idea as to the tools etc needed.

If you are intending to use just polystyrene sheets alone it will need a ply frame for support.

Also depending on the thickness of the polystyrene, in order to fit point motors etc it will be necessary to provide additional support such as 3mm ply and if the polystyrene is the type used for wall installation and is upward of 100mm thick then you will also need to undercut the polystyrene to accommodate such items.

In the UK there is a manufacturer of polystyrene based boards and if you look here you can see the general additional structure that you may need. Baseline Baseboards.

I have a foam baseboard for my layout, St Clements. Here are some threads that contain details on working with foam

working with foam

this is the St Clements thread and there are some construction details in it.

All of this layout was constructed with various forms of foam (and cork). The layout rests on tables from IKEA.

P.S. it is a just for fun layout and used Kato track

  I use 3cm foamboard mounted onto a frame. I use a band saw or jig saw to cut it. If you use a knife the angle of cut is critical otherwise it's torn rather than cut. It's rigid but can be flexed slightly to make an incline. The major problem is mounting solenoids underneath, though there are work rounds. I use wire in tube or hand operated.
Some of my stock was bought around the same time as yours.
Bead polystyrene is very messy to work with and the beads become statically charged. If it's cut with a hot wire cutter, the fumes given off are toxic so only cut it in the fresh air.