I build all custom trees for our saddles. They are made with a combination of power tools and hand tools. There are four components of the tree. The fork which consists of a wood horn such as a wade tree or a metal horn usually used on the slickfork trees and swell fork trees. The cantle, and two bars. The picture below is a hamley type wade. It is as close the original wade that Tom Dorrance had made at Hamley Saddlery in Pendleton, OR. Being hand made it is my version as each tree will have subtle differences.
Each component is glued up made of laminations of wood. This gives the tree great stability against wood movement from moisture and strength from the alternating grain patterns in the individual pieces. For the fork of a wade I use a combination of Baltic Birch Plywood (cabinet grade), there are 8 laminations in a 5″ fork stock thickness, the horn is capped with Red Elm which is a local wood here in Northeast Oklahoma. I can also make exposed horns out of either local woods or even exotic hardwoods. The cantle is made up of 4 laminations of Baltic Birch Plywood. Finally the bars are made from Tulip Poplar also called Yellow Poplar which is a hardwood (actually a member of the magnolia family. We use this hardwood for its lightness yet it is incredibly strong. It also has a property that when it breaks it usually breaks with the grain of the wood and not across. This gives the wood the ability to be carved down fairly narrow and also we can recess the stirrup slots on both the back of the slot and front. The other part of the process is that we cull all defects bigger than 1/4″. No knots in our trees, only high quality lumber is used.
This picture shows the bottom of the bars with the recess for the stirrup slots. A lot of trees makers do not do this because they use pine instead of Yellow Poplar and the pine just does not have the strength to support the cuts.