Difference between sculptamold and casting plaster - Model Railroader Magazine

I discovered dremel when building RC airplanes, also made extensive use of it detailing parts for car restorations.  Now finding good uses for the MRR.  I like the cordless, vari-speed version.  My first cordless disappeared with my ex-son in law.  My new cordless dremel is much bigger for some reason but still works the same.

The bits I use most often with a dremel are abrasive cutoff wheels, wire brush, tiny drill bit kit, and those that look like drill bits but designed to cut to the side (drywall cutter?)  Also if you look at the accessories shelf you can buy a regular chuck to attach the bits which is much more convenient than the collets that come with the dremel kits.  And the chuck is a necessity in order to use drill bits.

To do a rock face I apply plaster in sections using tinfoil.  I crinkle the tinfoil first to give the surface some texture and shape and lift the edges to form a bowl of sorts.  Then pour in the plaster.  When it just starts to thicken up I apply it and press it into place.  Give it a few minutes and pull the foil off as soon as the plaster begins to set, and then use an Xacto knife to blend the new section in while the plaster is still soft.  You have to work quickly because the plaster hardens fast once it starts setting.  This was always the biggest downside to this method for me- there is very little time to work in strata with the knife before it gets very hard to cut.  So it always ended up taking hours to get it to look really good.

The new trick (for me) was the dremel.  After the plaster was dry I used mostly a wire brush bit and a cutoff wheel bit to form the rock strata and crevices.  And also to flatten the rock faces in places.  Both of these bits cut through the hard plaster like butter but were pretty easy to control.  Then just a little touch-up and scoring with an Xacto knife to add some detail.  The idea is to work the strata into the basic rock shape that was formed by the foil.  The other thing I tried was using a very small drill bit to make a hole in a crevice to mount an outgrowing bush.  It was very easy, and I plan do this a bunch on my layout because like the effect.

Only caution- using the dremel on hard plaster throws out a bunch of fine plaster dust.  I have a mini shopvac and held the vacuum pickup near where I was cutting to catch the dust.

I am also finding the cutoff wheel and wire brush are useful for track work- cutting rails, removing burrs and cleaning/prep for soldering.