Fast forward to half term (i.e.
First step - superglue some 83mm golf tees to some 50mm washers:
Then, let a six year old and a four year old use your hot glue gun to make the bark texture. In hindsight, that was a rather stressful error as I frantically picked cooling glue off the dining table when they managed to miss the HUGE sheet of newspaper I'd put down. On the plus side, they certainly made random patterns which I hope will serve as bark texture when painted. Hopefully...
We then cut some pieces of scouring pads into suitable chunks and got them piled up into a reasonable approximation of a tree...
Now this is fine as far as it goes, and I've seen less convincing bits for sale, but I was thwarted at the next step - I have no wire brush to ruffle the dish-pan pads into more pleasingly arboreal shapes.
So, we have paused at this point but I shall inflict the forest's growth upon you as and when I find something suitably rough.