Short answer? Paperclay. Long answer follows.
I settled in to finish the long back foundation wall, literally before the storm and power went out. Above you see the carton materials wrapped from the left side wall and primed in Ceramcoat “Mudstone”, then the beginnings of the long traverse using various parts of egg carton. Then I noticed something.
A while ago, our thoughtful reader and observer Barbara W. had sent me a mold from Woodland Scenics. Although sized as “boulders” it occurred to me that at 1:12 scale they would make excellent rubble, the kind I was using in the foundation.
I reviewed my on-hand options and chose a pouch of Creative Paperclay. I had never worked with this material before, though it was on my list. I chose some of the larger boulder forms and filled the mold. I forgot about it until I started the back wall foundation masonry. Then I noticed that the molded boulders had a similar texture to the carton materials I was using. Like, really similar.
The dried paperclay is a remarkable material. It is extremely stable and lightweight, easy to trim, and as I was soon to find out, paints very well.
I reloaded the mold with the full set of rocks in paperclay to use around the rest of the foundation, and finished out the back wall with the few that had already dried (those in white), along with egg carton and packaging forms. It seems to take two or three days for the paperclay to dry thoroughly.
I applied the same set of acrylic layers and washes as the interior foundation.
Here’s a dramatic corner shot.
And the entire finished back foundation wall.
Although there is additional touch up and detailing to add, this needs to dry thoroughly. I could not resist gluing in some moss, though, to make it come alive. Thanks, BW, for the gift of the mold and allowing me to discover paperclay. The fun has just commenced.
nancyland.com 
Paperclay is amazing, I don’t use it often enough. I love the rubble mixed in the foundation, the extra dimension really makes it come alive.
I am only beginning to explore. It seems *very* versatile. Glad you like the rubble. Also versatile :)
I’ve never tried paperclay, although I’ve seen some particularly beautiful roof tiles made from it.
I’m glad the mold proved to be of use in 1:12 scale. I wonder if this versatility extends to making “rock” chocolates?
Oooooooh roof tiles. That would be a project! I wonder if one could build a mold of drinking straws, and roll the paperclay out… ooooh and painting them would be so great, finding just the right shade of terra cotta…
I saw in the Woodland Scenics catalog several other rock molds (moulds :) Chocolate boulders would be an adorable cupcake topping.
Many thanks to you, BW.
nancy, now this is a great mould – never seen anything like this either. and the effect is superb, exactly like stones! but obviously much lighter with paperclay. hey, thanks for sharing this :-)
Isn’t it, Marion? I was *so* pleased to discover its versatility. Now I want to try rolling the paperclay out to make dressed stone. I’m sure the internet is full of use demonstrations as well.
It looks very realistic!
Thanks, Cyd! I love “discovering” new-to-me materials :)
That looks remarkably real, great job!
Thank you, Bennie!
Such a great idea! There are two or three of those very molds in my local Hobby Lobby and I am always tempted to get one! Maybe now I have the perfect reason to!
I think so, Blake. The combination of the materials —egg carton and molded paperclay — is wide open to interpretation.
I always wondered about paper clay in molds. Good to know! I’ve never gotten around to using it, either. :D
I tried paperclay in a flatter mold, also, one with long smooth curves and details, and it worked well. Impressive stuff!