Here is a 3d printable front, and eventually rear intake guard for use with Blue robotics thrusters. It mounts underneith the stock nosecone, using two slightly longer M3 stainless bolts. This is an Open source CC by SA - Attribution project, so you may freely download, share, print and even sell the resulting guards if you like.
Project files and printable STL’s are there, this one prints well in ABS and takes a massive amount of support material to print, but the end result is quite strong. Please be aware that this WILL reduce your available thrust and top speed, and is only intended for locations where an intake blockage is likely.
The rear guard will be designed to slip over the fixed back nozzle and mounts to my reinforced thruster mount brackets with two M3 bolts. It’s not quite done yet though.