There have been many highly successful robots that are made primarily out of wood. Contrary to popular opinion, the wood doesn't 'just break'. It will flex a great deal before deforming. When it does deform, it is typically a very localized thing. Imagine ramming an aluminum bar hard enough to plasticly deform it. The entire bar is now bent. Ramming a piece of plywood might dent, even break through, the area that was hit, but the rest of the wood will not be affected.
Is it the right material for every application? Of course not. But it does have it's uses, and for the team with limited tooling it's a godsend.
Team 95 has been using wood, mostly 1/2" Baltic plywood for years with great success. Heres a sample of four 95 robots, 1998 through 2004 that used at least some wood.
http://www.lrt-uppervalleyrobotics.c...es/page_1.html
http://www.lrt-uppervalleyrobotics.c...s/page_17.html
http://www.lrt-uppervalleyrobotics.c...es/page_3.html
http://www.lrt-uppervalleyrobotics.c...es/page_2.html
http://www.lrt-uppervalleyrobotics.c...es/page_1.html
Many of those robots all preformed a similar task; picking up up balls off the ground. Rather then reinventing the wheel, the team chose to adapt an old design. By 2002, it had been pretty well perfected and the 'popcorn popper' was the result. A few more similar robots have been made since, all with the same frame layout and materials. The wood allows for a frame that is quick to produce, protective and just the right amount of flex. It could have been done with aluminum, sure, but plywood did everything just as well.
Use the material you are most comfortable with and best able to manipulate.
-Andy A.