Wood, saw and some nails. How hard can it be? EDIT: unless you are talking about the kids, that will take a female and about 3 or 4 years.
I was taking the 9 months into account Monsier M. Monkey. Those kids look about 3 years and 3 months old to me. (not Gary Glitter expertise on this mind)
Owt you can get your hands on... the ones on the outside look like logs, but they look like they're fixed to plywood internally. Facaetiousness aside... Marine Ply Timber and pressure treated half logs... Or if you're feeling adventuruous... cabin boards over a timber frame (which would be easiest in all honesty) You'll need to apply a roofing of course...
i built a 8ft tower behind the shed using fence posts concreted in ground and had an 8ft grp slide off ebay...stood 8 years till last week
can you not pinch your local bus shelter job done lol weve got on of those tree house things in the back garden which is used by my kids as a crack den looks like its made from old palletts
But that looks crap TBH... Like its on weeklys out the catalogue Tannalised 3x2 Battons, decking boards and 4" half round fencing posts would make a nice job and you'd end up with a proper job.
Don't use Marine Ply, it's only any good if either kept dry, or kept wet. As DaveD will testify having seen the state of the front of the house at TSC Island. It delaminates and falls apart. Did the whole front of the house in Marine ply at great expense - now it's falling to bits, delaminating all over the place. Apparently"Outdoor" ply or just normal ply well sealed with spar varnish will last ten times longer. Expensive mistake!