I used to use Hydrocal Grade-B. Not so cheap and comes in 78 lb. sacks.
Also there is Plastic Cement, which comes in 35 lb. sacks.
Regardless which kind of plaster/cement you use all tips remain the same.
just allow for the various drying times for each that you use.
What you need:
used window screens,
Mix a few cups of cement and when just right [paper towels soaked with
the mixture do not fall apart in your hands] take the soaked paper towels
and lay them on the cutouts.
The kind of poster paint which is a powder, mix in flour sifter
(buy your own) until mixed almost throughly. You do not want the color
to be consistant. Spray water on cement that is still slightly wet, sift
colored cement powder over wet cement, sparingly.
Use the flour sifter with the Poster Paint and a little plaster,
Spray a boxcar, and very lightly, sprinkle some paint/plaster mixture on
When it dries, it should very look OLD.....and very DIRTY....keep the mixture
off the trucks and wheels.
Scratch Building / KIT BASHING.
Take various parts from different kits, or parts you make yourslef,
then put them together for those that fit to make a new kind of building,
Use an exacto knife or small saw to trim wood or plastic parts to fit.