Full-size, rideable surfboard design. The 3d printed part replaces the traditional foam core. This still requires fiberglass lamination. For a good example method for lamination, check out meshaldrake's cardboard design at http://www.thingiverse.com/thing:4764 and http://www.sheldrake.net/cardboards/.
This board is 6'2" long 20" wide and 2 5/8" thick. Before glassing it weighed 6lbs, after glassing, it weighs 10lbs. A little heavy and probably over glassed. I used 3.5 kilograms of filament with some extra parts for practice glassing.
Earlier this year my son and I were having breakfast and admiring the surfboards on the wall. We decided that we could build one with the 3d printer. My Solidoodle was a little small at 6"x6" so I built a custom 3d printer with 12"x12" heated bed to reduce the number of pieces I would have to print. The board STL was generated with BoardCAD (http://boardcad.com). A more detailed description of the build experience can be read at http://hobbies.boguerat.com/3d-printed-surfboard/.
UPDATE: Added pic showing translucency. Also, had this out in the water and besides being a bit small for me it rode well, decent float. Seven cells took on water in two groupings. I'll have to drill small holes to drain the water and patch. Will update the blog with pics and procedures.
UPDATE 2: Had the board out today and it was AWESOME!!! Finally had a bigger day with some meat on it. The lamination is holding up well. There are some white spots where I smacked it up against something and the patches are holding well. Working on the next design, a big guy tri or swallow tail for me.
UPDATE 3: Uploaded the sliced STL I used for the mini board. It slices with 3 perimeters which I couldn't replicate with the full-size STL.
A more thorough build is detailed at http://hobbies.boguerat.com/3d-printed-surfboard/
The board design is re-dimensioned (scaled) from the default Shortboard template in BoardCAD. The holes were cut out using Solidworks. The large stl was cut down to size with netfabb. It was sliced with Slic3r, gcode generated with RepetierHost, and printed on a custom 3d printer.
The parts were glued together with acrylic solvent cement and the whole board was glassed like mesheldrake's cardboard surfboard.
You really need to check out my website for the good gouge on this board.
The fin inlay was too tight so I used a razor blade to trim as necessary. I should have just scaled the lightning bolt down and printed a second time because I ended up cutting myself. I'll post a solid fin design later without the inlay. For the center fin, print two fins scaled to half height and mirror one so they can be glued together giving a taper on both sides.