Could you ask more questions? LOL let me see what I can do to answer some/all of them.
-Can't remember if I took more pics or not probably if you search through my threads you might find some.
-I used exhaust pipe because I could weld it and coat it the way I wanted. I looked at a type of plastic (abs? or something) but couldnt find anyt locally.
-I read in a 4x4 mag 2.5 inches minimum, there was a thread very recently in the 40-55 section about that as well.
-One thing I did to help deal with water at connections was make as much of it 1 piece as possible I also coated it with a ruberized coating to seal it.
-I dont think theres any problems with it moving while driving the hole coming through the fender is a snug fit.
-Made my own air filter housing, took the smallest filter I could find cut it in half and then made a box for it and sealed it in. Not worried about water getting in it would have to be 4+ feet to cover the air filter housing and maybe worry me. But at that point the whole engine would be under water and I'd have bigger problems.
-I made the cap, plan on trying to find a cap from a safari snorkel at some point but the concept is quite simple. The housing is a box, the tube comes through the bottom and stick up through the bottom a little bit. When water comes in it hits the back of the box and drops down and the air gets sucked in. Around the tube are drain holes. Also if you look the spot on the feder is lower then the carb so if a little bit of water were to get in there it would collect at that low point anyway. You can always just turn the intake the other way though. I have seen dozens of pics and video of snorkels now that dont have any kind of box just a piece of tube that faces the back with a slight downward bend to keep water from being able to get sucked in, water doesnt move uphill as I'm sure you know.
Hope that all helps

, and my pig is ORANGE

not red
Fanatic soon to be 2 time alumni they are the same thing.