Mister Bean is a 10 ft trimaran built by Mario Falci. The material used for this build is polyurethane. When you are not familaire with the material you can find a detailed description by the builder over here. The website is in Italian but that should not be a problem for your friend Google Translate.
The drawings are in DWG format. You can open this with CAD software. With the Autodesk Viewer you can do this for free (you need to register). This works best. There are other sources out there but this one works best in my opinion.
This trimaran design is for the more experienced builder.