/diy/ - Do It Yourself

>>788091
The semicircular thing in front of the fish is an obstacle that leaves an oscillating vortex wake, this oscillating vortex wake makes the fish swim. There's more about how this happens here: http://www.people.fas.harvard.edu/~glauder/reprints_unzipped/BealEtAl2006.pdf

>>788375
>>The issue in my case is more that my printer is shit and will take forever printing something with more than 50% infill
Even with 50% infill 3d printed parts can be pretty strong. Especially if the forces you apply to them are in the plane they were printed. You should do an estimate of how much force your fish is really going to be under and see if you really need more than 50% infill or fiberglass(start with the torque your servos can apply).

After reading more about this specific fish robot(see: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6181603)), you could probably get away with really really low infill percent. A large hollow with honey comb on the inside can be pretty strong. And looking back, you really don't want a solid structure, because then you'll have to add a huge amount of ballast to make your fish neutrally buoyant.

Now if you must do fiberglass, one thing you can do is us your 3d print as a core, that is you wrap your 3d print in fiberglass and not bother removing it. Although if you use PLA, you can use the chemicals here to dissolve it: http://ifeelbeta.de/index.php/support/support-full-disclosure

Not sure if any of these things will damage fiberglass resin though. Pic related, a part made by a similar process, wrap dissolvable print in composite, cure, dissolve stuff, done