While flying sailplanes the slope soarers and later the thermal guys got into "unbreakable" EPP sailplanes. EPP is that soft flexible foam that shows up in heavy electronics boxes with your new TV set.
Gets a bit complicated when you put an engine on the front, but can't help wondering that id should be possible to build a really robust, really durable and really ugly but virtually unbreakable CL BASIC trainer using the stuff.
I probably missed it, but has anyone tried?