No. Balsa can be purchased from any site. The team members alone must decide which pieces of balsa to use when they construct their structure. Copies of the receipts will need to be given to the weigh-in judges at the tournament. It is important that the wood meets the requirements noted in the problem section E.9.b.
Oversized Wood: any piece exceeds 1/8”x1/8” (.135” x .135”) at its cross section (not assessed if it is an irregularity of that piece and the rest is within limitations) will receive a “weight-held” score of zero.
The team should refer to the problem statement and Program Guide (a link to it is available on the Resources page) for the restrictions on legal balsa wood. For other questions, the teams can submit their questions for clarifications on the Odyssey of the Mind website.