Brent,
Welcome to the party. These guys are a wealth of information and have been essential to the success of my fledgling efforts. I can't help with plaster on wire, but I can tell you what I have used as a base--1/4" plywood under 1" extruded foam. This has worked well for me. It has the advantage of foam for "planting" trees and carving terrain, while having a rigid base for securing switching motors and wiring harnesses.
Richard
Brent:
In the distant past I tried plaster over window screen. If you go this route I would strongly recommend dipping paper towel pieces, or small rags in the plaster, and draping them over the wire. Plaster drips through the wire otherwise.
As mentioned above, blue or pink styrofoam makes good mountain bases. Use white or yellow glue or latex caulking to hold the layers together. Light weight and strong, and less dripping where you don't want it.
Dave in Oshawa
Welcome. Scenery suggestions abound, and carved foam has seemed to be the popular style for several years. That does not mean that folks aren't using plaster.
I've always been comfortable with Hydrocal and continue to use it. I don't expect to move the layout so the weight of the plaster isn't an issue (new layout for new space if/when I move). I had more area of scenery to cover in my previous layout and did use some wire mesh for the base form then. I discovered, however, that the plaster itself would be the support once it was in place, so for me the effort of shaping the wire mesh was too time consuming. I build up the basic form of the "hill" with wood risers, a mesh of cardboard strips, and/or balled up newspaper for smaller slopes and then cover with paper towels dipped in Hydrocal slurry. The newspaper stuffing underneith is usually removed from below once things are set up. I found that "industrial" style paper towels - the kind used in a business or company washroom - work best for me. Areas that will see exposed "strata" then receive a troweled-in layer of thicker plaster that is carved before it sets completely.
There is some really nice scenery out there made with stacked up foam and I always read the articles on the new techniques, but the "traditional" style still has a following with good results.
Bill
I have built quite a number of layouts, most of them using the old fashioned plaster over wiremesh for scenery. I won´t be doing this again. The process is quite messy, it is quite heavy, "planting" trees is awkward and making changes messy again. Styrofoam is much easier to use and to shape.
Welcome.
I will add another vote for foam to build your hills and mountains, as well as a 2" thick sheet for your layout base. It is light and easy to work with. Score and snap is the clean way to cut it, however, when it comes to final shaping, it can get messy. I recommend having a shop vac handy. Also, spray a little anti static spray on yourself and the area, makes life much easier. I have a Surform Shaver which I find very useful shaping the foam to contours. The other Surform tools each have their place, but I find this the most useful.
I use inexpensive latex caulk for an adhesive. It holds immediately, but gives you some work time to move things if necessary. I have read that white and yellow glues do not completely dry very far in from the edges, as there is no air movement. Be sure whatever you use is foam comaptible. Some products eat the foam.
I like it for a base, as it can be carved for below grade features. It is quite strong and several folks here have indicated they have used 2' centers for support.
You can also cut foam with a hot wire tool or hot knife. They make very clean cuts, but also make smoke, so have plenty of very good ventiltion if you use one.
Good luck,
Hi Brent and Welcome into the hobby...
The following link may be of help to you to see the foam and laying of plaster soaked paper towel
http://www.xdford.digitalzones.com/quicklayoutconstruction06.html
and the parent website with the links may also be of use to you for other stuff
http://www.xdford.digitalzones.com
Regards (and Happy New Year from Oz)
Trevor