Rainshead has made a few. Here is a link.

Here is a link that might be useful: tombstones

I havn't thought much about Halloween but one of my future projects is to research papercrete techniques and make some life-size toy soldiers or nutcrackers for outdoor Christmas decorations. It won't happen this year... too much on the list with higher priority.

Why papercrete Jazz?
My experiments with papercrete do not bode well for wet wintery weather. It's like a sponge in a BIG way, and not much cheaper than other techniques especially if you have to seal it against the weather. It doesn't fall apart but it sures does get heavy. My concern with toy soldiers would be their stick like arms and legs could break under the water weight absorbed if you dont use welded armatures.
And as a ' clueless concrete newbie I can only imagine what will happen to soaking wet papercrete if it freezes. You are z7 so it's probably not a huge problem for you.
If you want super light weight and durable, that does not suck up moisture try the sand like perlite made for use in light weight concrete.
Once cured absorbs very little moisture from it's surroundings.
Very light and strong, beautifully easy to carve and shape with hand tools, and if you use integrated colors you will never need to paint those soldiers even twenty years from now. :)

Thanks TE, you've just done answered a lot of what I wanted to find out researching the papercrete. I had said papercrete because I thought it would be super light, almost like paper mache. If it soaks up water easily then I will avoid it.

Papercrete used in construction of houses seems to be mostly in very dry countries.
I like papercrete because it can be very claylike and molds and shapes nicely and is super light when dry.
If there is some way to stop it from absorbing water I would love to hear about it.
I put 5 coats of concrete sealer on a papercrete brick and it still absorbs rain water like a sponge.
I made an ugly sungod from paper crete and when it rained the hooks I had embeded in the back for hanging it let go and it fell to the ground.

I feel I have learned alot this year about all types of concrete and their strengths and weaknesses. I'm very happy with my technical progress. This fall and winter I will be working on my artistic skills so my projects have a nice appealing look. I can't keep making striped bowls forever.:)

I have 6 bowls, troughs, and lanterns that I'm going to sacrifice to the winter Gods to see exactly what happens when they are exposed to the huge almost daily freeze thaw tempurature swings we experience here.

I'm jealous of your zone 7. I would be in tufa heaven in a warmer climate.:)