As a potential change of pace I'm planning on a simple roundwood structure this summer. I have three small oaks that need to come down for safety reasons, and a lack of well-placed trees in which to build a treehouse for my kids, so the idea is to use the roundwood from the oaks to build the first level of a multi-level playhouse that climbs up the bank to the south of our property. I could go mortise and tenon if necessary, but I'd like to explore the options for a more traditional approach. Other than Ben Law, is there anyone out there detailing the necessary methods for attaching roundwood timbers to one another? Especially regarding scribing the form of one timber onto the other.

If not, I'll just finish up with some slightly awkward looking reductions around my joints.