I put the crumpled paper in plastic grocery bags because they don't hold their shape when they get wet.
I line the tunnel with styrofoam or cork if it is curved, so I do not need to remove the paper after the plaster dries. I have removed some paper when changing terrain, and it does stick to the plaster cloth, but it is not difficult to pull out.
I also put a flat piece of styrofoam where the portal will go, so that I have something to which I can glue it.
I'm sure other in here will have other suggestions. Wait a few days, review them all, and choose the one you like best.
Dave
Lackawanna Route of the Phoebe Snow
Some of the paper will stick to the plaster cloth but most of it should pull away if you are carefull.
In cases where it is really stuck just carefully tear the paper and leave the stuck portion where it is. I found that the shell when completely dry is fairly sturdy and will resist some tugging at it.
Bluehills described what I did before I went to foam mountians. I used a little masking tape to change the shape of the newspaper pile some. I never did figure out how to plant tall trees in the plaster cloth scenery. I never bothered with the cardboard shell either. I stacked the newspaper balls and hung the cloth. It was fast and gave decent scenery shell easily.
Caution, do not wash stuff in a sink. even hands, it will dry in the trap. Have a five gallon bucket to wash in.
Trainman:
Having trouble replying to your e-mail.
I'll try a PM.