Thanks for all the great feedback on the Perch posting. There have been a few topics brought up that are worth addressing. The seat material can be any wood that you care to carve. If you are using a softwood such as pine, I suggest using a 1 1/2" to 1 3/4" thick piece. If you are using a hardwood, you could go as thin as 1 1/4". The perch presents a great opportunity to become accustomed to drilling and reaming. Those who are new to the process, may benefit from creating a practice seat out of softwood (my first practice seat was 2X4's glued up!). This way the process will show it's quirks during the dry run.
As far as tools for the perch, I would suggest the 6 degree reamer from Elia Bizzarri at handtoolwoodworking.com. This is one of the last great woodworking bargains. The seat of the perch is only scooped out 5/8" at the deepest point. This is shallow enough to carve with a gouge and finish with a scraper, but if you are thinking of making more than one, I suggest the travisher that Elia sells (based on my design, but I have no stake in the business). It's a great tool and works beautifully. Perhaps your first perch sale or gift can cover these costs!
By its nature, the perch is a custom object. The goal is to tilt the sitter forward to encourage the lumbar curve to do its job. Each person will need a different height. The perch that I show is good for an average sized person (finally being average pays off!). I custom size them by putting books under the feet of the perch or the sitters feet until they are comfortable. One of the reader comments mentions a web page that describes the concept beautifully
As I mentioned before, the perch was a collaborative effort with input from Galen Cranz and Curtis Buchanan. Galen has literally written the book on chairs. The problem is that she finds that our entire relationship to chairs is faulty at best and unhealthy at worst. We live in a world designed to suit the work and dining surfaces we create, and let our bodies take up the slack! She inspires me to try to improve the design of my chairs to better suit the sitter. Her book is a must read.
The Chair: Rethinking Culture, Body, and Design (Hardcover)
by Galen Cranz (Author)
I hope these diagrams are easily read. These are just suggestions for the legs, if you are without a lathe, just shave the legs with a drawknife and round them with a spokeshave, don't let tools stop you!
Here is a video of the leg turning, I hope it helps