tunnel facings

I just went at it with a screwdriver and painted it slate gray or black with pieces of real stone right at the entrance. I can get a couple of pictures tomorrow.

You can take 1/2 think foam and make a good concete portal. Just cut it out and paint and weather accordingly. 

Found one

I use Precision Board, it's similar to foam but much more dense. It can be cut, carved, sanded and painted like wood. You can get more detail and it takes spray paint nicely. It's also great for for buildings.

I built my tunnel portal using celotex.   Stacked up like a layer cake. I suppose would work the same with foam.   Held together with white glue and screws.   Painted with light brown latex paint.  Then cover it with water + white glue mix and then spread fine sand over the glue.   Use dark grey paint for the concrete portal.  Some black spray paint to make it look like the grime and soot from the locomotive exhaust .   Paint Tip.   Go to Home Depot or other building supply store.  They will sell a 8 oz paint sample for $3 bucks.   I got a nice grey color called "Antique Tin" that I used for the concrete.

Steve

I wanted to match the Lionel postwar portal with a 2-track version. I carved it in pink foam:

Built mine out of 1/8" Masonite backed with green foam to add depth. Do not use Rustoleum sand paint on foam. It dissolves it!

Trainman2001 posted:

Do not use Rustoleum sand paint on foam. It dissolves it!

Actually, I sometimes do that on purpose. A VERY light dusting of it softens the edges and nicely simulates the look of old weathered concrete. Best to do it over an initial layer of hobby acrylic.