I have used wire hardware cloth in making troughs in some of my classes. It works well if the mix is rather "dry" to minimize the tendency for the mix to fall off the vertical walls. I have never use it for anything as large as you plan. Try making a smaller trough first to get the feel for it. I also made a small "Adobe" house using the wire cloth. The gable roof was made in one piece and colored different than the house. The mix used made it appear like adobe without separate brick marks.

I second fred on the dryish tufa with the wire mesh

I actually use chicken wire to help the tufa have something to cling on to when doing long vertical surfaces, such as the wall on your dog (hobbit) house. You wante a peanut butter consistensy... something that wont run, but will also not crumble.

Also, if you want the "hobbit" house effect, I found out, by accidentally using too much dye, that the dyes from Olde World (particularly terracotta and the bright yellow-rust color) will give you that effect. And it wont wear out with time.

As far as the pre-mix, I don't know if it'll be easier and cheaper to just buy your portland (white), sand and peat on your own. It's not that difficult to mix, although, a doghouse will involve a LOT of mixing.

You're going to want rounded edges, so I'd probably dress an existing structure so you will have something lighter that also requires less tufa

Good luck on your project and be sure to post some pictures :-)

I have played around with hypertufa and concrete sculpture using sytrofoam wrapped in chicken wire as a base. It has held up fine. I don't know how big your dog is (smaller than our Lab I hope), but your hobbit will no doubt need some support other than hypertufa. Maybe a rigid foam board covered with the wire and tufa would work. Good luck!

gord_nm beat me to it. Styrofoam is completely stable as long as no UV light hits it. It also provides good insulation. The wire mesh with cement (ferrocement) can be remarkably strong.

This doghouse could wind up being a permanent structure.

...old pos, but for information sake. Check out how some of the monolithic dome homes are done.

I'd recommend some rebar, with hardware cloth or something similar over it... then apply your mix to both sides.