So I have decided I want to try and make some chairs. The design I want to go with requires steam bending some wood for the back legs similar to a Boggs style chair. This means my next project is going to be that I have to build a steam box.

The plan for my box is a simple plywood box that will be roughly 7"x 7"x 48" long with stainless steel rods passing through the sides to serve as a shelf for the pieces. I plan to use exterior plywood for the box and I was considering adding some rigid foam insulation on the outside to help hold the heat. I'm not sure if this foam insulation is necessary as it is not something I see a lot of. I would expect the steam to condense inside relatively quickly without some sort of insulation.

My big question and the reason for posting is about the steam generator. I bought an Earlex Steam Generator a while back for this purpose and I'm curious if this one generator would be enough for a box of this size. Is it worth trying to steam bend wood with just one of these generators or should I just add another Earlex to this box and call it a day?

Basically I'm just looking for any advice from others that are steam bending using this setup. Should I have two steam generators going to be sure I have good saturation or will one be fine? Am I missing something with this design or should I be looking at a different design all together? All advice would be greatly appreciated. This is a very new road I'm traveling down.