cutting them out is the easy part, getting them glued and/or stapled with brads is harder. Then putting the arms and getting it to open with the correct balance was difficult also for me.
If you were to have them sent unassembled, it would be best for the builder to put them together first, then...
In my opinion, the only difference between bantams and full size chicken use is the weight of the treadle and lid. And you might find it less expensive to find someone in your location to build them rather than have to pay expensive shipping costs. Also, you could monitor the building process...