There are various types of elm....so the best design will take into account the best qualities of the wood. A flat bow design with narrow tips is probably your best bet....although elm has been used in the past for ELB designs. Again, find out what kind of elm and then use the formulas in TBB to design your bow.
Elm is great in tension but a little weak in compression. Heat treating the belly will increase the performace of the bow.
