When I worked at HSN (Home Shopping) in the set dept. we would use a spray bottle with Lacquer Thinner on the styrofoam to give it texture then spray paint it to make it look like rocks. That was fun.
I'll bet
One of my oldest son's friends went to The Art Institute of Pittsburgh after high school ... ended getting involved with creature makeup, model building, and eventually animatronics. Paid off very well for him. Sounded like it would be a gas.
The technique Glenn suggests is to use a
Stanley Surform Shaver, which has a curved blade to round and shape the pieces after initially cutting them out, and then use a heat gun to melt the surface to smooth it out. I have a nasty little wood rasp/file I'll probably use as well, to put in some striations. The mortar, of course, adds some (rock-like) texture and serves to encapsulate all the separate pieces of styro as a single unit.
Even at 60 yo, it bites to be an adult and do what needs to be done instead of what you want to do.
I hear ya brother - today's menu:
Go thru a butt load of mail, paperwork, and receipts (10+ to 1 ratio of junk/crap to anything valuable or really important)
Call gas and electric companies and tell them to take us off the mailing list for their (at least once once per month) solicitations for "homeowner protection plans" (gas line from the meter to the house, electric lines from the weatherhead to the meter, water lines. etc.) Just tired of sorting thru and handling their crap (circular file) on a regular basis.
Call Salvation Army and told them to take Mom off their donation solicitation mailing list, beings as she died 17 years ago (... save a tree)
(Start to) clean up kitchen ... didn't get to mopping the floor yet, but made good progress anyways ...
Pull Woman's car out of the garage and see if I can spot where the exhaust system is broken (mid-section of the car, looks like it might easy enough to cut out the bad/rotted part and sleeve it ... won't know for sure until I get it up on the ramps) Note that window that I fixed several months ago is inoperable again ... hopefully just a clip came loose and nothing is actually broken.
Replace run cap on the Coleman compressor and put it all back together. Yippee: something actually
fixed ...
Start cleaning up the garage and putting stuff away. Got that about 50% done ... last part is the worst though (putting small odds and ends away)
Unclog whole house vacuum cleaner (happened when I inadvertently sucked up a paper towel while vacuuming the garage)
Look at back of washing machine to see how involved it's going to be to get to the switch for the lid (plenty) Likely temporary fix: bypass the switch.
Didn't make it over to Mike's to pick up my fittings for the reverse flow UGF ... I did however manage to gather up all the scrap styro (EPS) over in the polebarn for the backdrop and bring them over to the garage

... looks like I have plenty, mostly 2" but also a little 1 1/2" ... think I have some 1" in the basement that I can use as well.
I brought over some 1" polyiso
cyanate as well ... but after thinking about it a little bit, I'm not really sure that would be the best thing to stick in the tank.
Also found my coping saw (sans handle, which I think broke at some point and was tossed) ... can probably use one of the knobs for the levers on my rear remote valve for a handle.
Life is good.