Roy,

     I see a lot of clinics you could do here for all of us to enjoy. For me you can start with scenery... Your rocks

in the hill areas is what caught my attention. Looks good.

Avis

I've had a blast following along.  Looking forward to your foamcore clinic!

I pretty much make rocks the standard way. I use heavy paper like the old-fashioned brown shopping bags draped over braces made of scrap wood. Then I use masking tape to fill in any gaps and fasten it to the braces and surface of the layout. Then I cover it with a layer of hydrocal. I use sculptamold to cover any imperfections. To form the rock strata, I like to use a utensil artists use, often called a "mighty knife". I allows me to apply and work the hydrocal. You have to work fast with the stuff and the mighty knife makes it possible to cover a lot of surface quickly and create stress and rock strata as you go. It's a nice tool for this.Sometimes I work crumbled ceiling tile into the hyrocal for rock strata. I also use Woodland Scenics rock molds with the hydrocal and "plant" the rocks in the wet general areas.

Next comes the coloring. I use what I've learned as an amateur  artist. You need a base color to apply to the basic rocks. Something in the order of brown to gray depending on what area you want to model. I use a medium gray. Then I use white, black, raw umber and yellow ochre acrylic paint for the highlighting. I sometimes mix the brown colors with the white and black to get off-colors. If you put a small amount of paint on a tapered brush or fan brush and gently swipe the rocks with it, you can highlight the rock without overpainting the base color too much. The crags of the rock will pick up the highlight and make a good contrast with the base color.   

 These acrylics are applied to the base color. The "mighty knife" is at the top (obviously well used).

Blue Mountain was made using all the techniques described.

I used Woodland Scenics Talus for outcroppings common to the mountains of PA.

I tried to recreate Sidling Hill Tunnel on the EBT as close as I could.

Here are some ceiling tile rocks.

Roy,

The ceiling tile rocks look great, (as does the rest of the rockwork)!  I would never have thought to use ceiling tiles...thanks for the tip!