A lot of person built a frame out of PVC pipe. I wanted something different so I used a 6-way drainage fitting from flexpvc.com. It has four 4" and two 2" ports. The picture on the homepage was created using the free SketchUp program. I have never used an autocad program before but I found that SketchUp was the best for me. Yes, it has a learning curve but it is pretty intuitive. One thruster is inside for the up/down movement. Two thrusters are attached to the 2" outlets using 1 1/4" pipe and pipe fittings. I supposed you could use just a flat piece of plexiglass in the front for the camera but I think the dome looks cool. 4" drain covers on the top and bottom were used. They are probably not needed but used anyway just to keep out the stray floating object. There is a cap in the back with a disconnect for the tether.
I used 4" PVC pipe to hold the camera and tilt motor in the front and all the electronics in the back. I made the 4" pipe waterproof. I accomplished that by using silicone around the dome and cap joints. On the other end of the pipe I used a knockout plate through which I put bare copper wire that fits perfectly with a red wire coupling. I then sealed that with potting epoxy. I used the bare wire instead of just potting the electrical wires because of the possibility of water creeping in from inside the insulation. I have to say it worked really well, not only from a waterproof standpoint but also because I can easily disconnect the various components if needed. Turns out that with the pipe waterproof the ROV is just slightly buoyant. Also, in case you don't know, wax will not seal out water that is under pressure.
I designed the frame so I can remove the thrusters and legs from the main body. I did that to facilitate storage in a big cooler. Everything fits - the batteries, ROV, control box, and tether. Using the cooler makes things easier to carry and keep together. I can also use it as a seat when operating the ROV.
I used 4" PVC pipe to hold the camera and tilt motor in the front and all the electronics in the back. I made the 4" pipe waterproof. I accomplished that by using silicone around the dome and cap joints. On the other end of the pipe I used a knockout plate through which I put bare copper wire that fits perfectly with a red wire coupling. I then sealed that with potting epoxy. I used the bare wire instead of just potting the electrical wires because of the possibility of water creeping in from inside the insulation. I have to say it worked really well, not only from a waterproof standpoint but also because I can easily disconnect the various components if needed. Turns out that with the pipe waterproof the ROV is just slightly buoyant. Also, in case you don't know, wax will not seal out water that is under pressure.
I designed the frame so I can remove the thrusters and legs from the main body. I did that to facilitate storage in a big cooler. Everything fits - the batteries, ROV, control box, and tether. Using the cooler makes things easier to carry and keep together. I can also use it as a seat when operating the ROV.