I've done a fair amount of DIY projects before, some that turned out great and some that I shall never speak of, and no matter how clearly I can envision what I want to make, at some point I have to stop myself and think, "Wait, how the hell am I going to put this in that, or house it all, or waterproof it without a whole tube of silicon, etc."
So everyone has, over their prideful years of DIY'ing, developed basic techniques and found certain materials that can get them through most projects that have dead-ended.
So post 'em! But don't say duct tape. I think we can all agree it's an indispensable DIY material.
I'm toying with 3 materials fairly new to me for casting into a mold to cover a headlight I'm making (not to put on the bike, but to put on my head):
1. Epoxy Resin (not the small double tubes, the kind that comes in a quart can from a crafts store for 10 bucks), because having a see through project would be sweet.
2. Styrofoam and acetone - the acetone breaks the polymer bonds and turns it back into a monomer polystyrene. Until the acetone dries, it's essentially a plastic "slime" that you can mold with great ease. The longer you flex and mold the slime, the weaker the bonds are and the more brittle it will be.
3. Fiberglass drywall tape or any fiberglass fabric - probably useful for reinforcing either of the above, especially the polystyrene since it can be brittle (think of the plastic forks that snap when bent).
See, I like building projects from the ground up, so the bike headlight from the "Total Geekiness" thread that uses a malibu yard light as the lamp body could have been made like this in my mind. (granted, the malibu light is perfectly sized for a bike headlight and looks professional).
If you need to fabricate any type of water-proof housing, I'd recommend Starboard. It's a marine plastic that you can use to fabricate items, using your tools without worrying about it ruining your saw blades or drill/router bits. I used it to build a battery box for the LIFEPO4 battery pack I made for my e-bike.
We recently built a small plywood boat and that was the first time I used epoxy resin. It is good stuff, but expensive. It took about $35 worth to seal up a 7 foot boat.
I never heard of the styrofoam and acetone trick. Have to give that one a try. Thanks for the heads-up.
This probably won't be of any use to you, but I like using hardware cloth covered with motar mix. I once read an article about a guy who built a boat from chicken wire covered with concrete. I have sealed two very leaky foundations by glueing 1/4" mesh screen to what remains of the foundation then troweling on a layer of motar mix. Both times it has worked very well and in both cases it's still holding up. I don't see why you couldn't build other things from it.
Actually, I have used something like that. Last year I found a small box of something called "Magic Mix." It was a kids craft where you'd add an unidentified powder with a small amount of water, and within 45 minutes it would dry nice and hard. Basically, it was cement.
I used it to make a small handheld LED flashlight for a friend (mostly because I was bored and thought, "Hey! Concrete Torch!") It was...interesting to say the least. I even stupidly froze the linear switch and had to partially carve it out to free it.
The styrofoam/acetone trick is lots of fun. Take a tiny amount (an ounce to start) of acetone in a glass and drop in the styrofoam. It begins disappearing as soon as it hits the acetone. Pull it out the polystyrene goop that forms and you could probably do a lot of stuff with it, as long as you're careful about NOT igniting the acetone. This is the only way I can think of that you could use polystyrene since it decomposes from heat (which is why it isn't usually recycled), while PET can always be reformed from heat.
Sekine RM40 1980, Miyata 1000LT 1990, Raleigh Mixte Sprite 1980, Raleigh Grand Prix 1979
How can it be that nobody has mentioned duct tape yet? lol
On a serious note - silicon sealant (the stuff in the squeeze tubes) has come in handy for me many times, either used as a waterproof adhesive or general purpose crack filler. You can build it up in layers and make pads inside your custom made cases (sealed with silicon) to stop batteries, etc. from bouncing around. It's still a bit flexible after setting so it suites this purpose well, I've found.
And silicon sealant is up there too. I'm never quite sure which one to use, as there are many different "brews" of the stuff. I tend to stick with the aquarium grade silicon, though it is a bit expensive. Only thing I don't like about it is how messy it can look after you glob it on, but that can sometimes be smoothed out with a brush dipped in spirits.
Another great and versatile material that I'm sure no one has really used is artist's acrylic gel. Acrylic paint is basically a polymer base with pigment, and the polymer base is also sold alone and called "gel". It's white when wet and clear when dry. There's a thin and thick version, as well as a few other variations. It's pricey, at least $50 a gallon, but a little can go a long way. It really goes far if you thin it with distilled water, which is how I use it to stiffen and water proof canvas for certain projects. I met the owner of Golden Artist Colors once and he explained how it used to be made from ground methyl methacrylate (plexiglass), but not any longer.