After a year of using my Z with rubber-bands holding on the lithium battery packs, I'm getting really tired of fighting it. Ever since I did the battery mod, I've been wanting to mould a new back to cover them up since it's really hard to slip in and out of my pockets now. I decided to write up a how-to guide as I work on this process. If anyone has suggestions along the way, feel free to jump in.
So now it's time to get started. (This is the part where I really wish I had a digital camera, but I'll see if I can borrow one.) Last weekend I started shopping. I needed something that was the right size and shape, with smooth rounded corners. Primarily I wanted something that was the right width, and as long or longer than the body of the Z. What I found were small transparent plastic cases for holding screws or craft pieces. These are sold in all different sizes and shapes. I actually found one that was the perfect size in the fishing lures.
Initially, I was going to just use a dremmel to cut up the case and use it as it is. But why should I do anything the easy way? Instead I decided to try my hand at vacuum moulding. There's a lot of info about this online, and the concept is really simple. Make a negative, drill holes through it, and connect the holes to a vacuum line. Clamp a piece of plastic over the top, stick it in the oven, and when the plastic starts to sag, turn on the vacuum to fill your mould.
Last night I found a box for a power supply, lined the bottom and sides with a single piece of aluminum foil, and mixed up a batch of plaster. The plaster was left somewhat thick, and poured into the box to more than an inch deep. Then I took my plastic case, covered it with vaseline, and pressed it into the plaster. You will want to push it in at an angle to try and prevent air bubbles from being trapped underneath. Get as many out as you can, but any remaning will be filled later. You will want to press your plastic case in at least 3/4" deep. Shake and rock it to get the plaster to settle right up against the sides. You'll need to work fast, as the plaster will start setting up in about 5 minutes. Note that the plaster will get very warm when it starts to cure!
Once everything is in place, let the plaster sit for at least an hour or two. It will still be damp, but you want it solid before moving it. Now you should be able to gently rock your plastic case and have it pop right out of the plaster. Let the mould sit overnight, then pull it out of the box (either by turning the box over and gently letting the mould drop out, or by cutting the box off). If you packed the aluminum foil nice and tight against the inside of the box, it should come cleanly off of the plaster.
Now look over what you have. There may be some air pockets or other defects to fill in. Mix up some more plaster and fill in the holes until you have a clean mould. At this point you will need to let the plaster sit for a few days to dry out, but the mould is nearly complete.
What's next: After drying, the top surface will need to be sanded flat and holes drilled through the mould for the vacuum.