Well, here's some good news! I'll show you how to convert it into a refillable "Air"-osol can (literally - it uses compressed AIR) so you can use it as a personal emergency misting device, flamethrower, or simply something to cool you off with.
If you like this instructable, please vote for me in the new Pocket-Sized contest! I could really use a leatherman :D
As a side note, if this instructable looks really long and complicated, it's not, really. I just made it really detailed and informative so that it's foolproof XD
Step 1: Gather Tools and Materials
1. An empty mini AXE deodorant can*
2. 2 inch long tire valve**
3. 1/2" PVC slip-on endcap
4. 1/2" PVC pipe - just enough to fill the length of the endcap completely
5. Electrical tape
6. 2 regular-sized rubber bands (not shown)
7. A disposable glove - you don't want to get any of that glue on your hands, do you? XD
- I used this just because I found an empty can just lying on the ground (yeah, lucky! :D). You could probably substitute a similar can for more air volume if you wanted to.
1. PVC pipe cutter or hacksaw
2. Dremel tool with small drill/ suitable attachment - well, you want to make a 3/4-1"-ish hole in the bottom of the AXE can
3. A hand file that's rounded on one side - if you want to further fine-tune the roundness of the hole, which is not totally necessary (optional)
5. PVC cement
6. PL Premium Adhesive cartridge, OR superglue, epoxy putty, etc - something that can bind PVC to metal)
7. A caulking gun - if you're using PL Premium
8. Bicycle pump - better if it has a built-in pressure gauge. (not pictured)
Step 2: Drill a hole in the bottom of the can
First, make sure the AXE can (or similar) is EMPTY before you puncture it.
Then, drill a hole that's about as big (no bigger) as the inner diameter of the PVC endcap mentioned in the materials. You can do this because the of the dremel's high speed - once you drill through the can, just force the bit into the edges of your hole while it's spinning and it will enlarge the hole.
You may have to use the rounded file (also mentioned in the materials) to make the hole more circular and smooth.
Step 3: Cut the pipe and cement it to the cap
Insert it into the endcap as far in as you can.
Then, mark the part of the pipe that touches the endcap lip.
Take the pipe out of the endcap.
Cut it at the mark you made earlier. It should be about an inch long.
Apply PVC Cement to both surfaces - the outside of your new pipe section and the inside of the endcap.
Re-insert your 1- inch pipe section into the endcap, making sure to twist it all the way in.
Wipe off any excess cement.
The end result should look like the first picture.
Step 4: Drill Another Hole
Make sure to make it a tad bit larger than the middle of the "tube" section of the tire valve.
Step 5: Tape the tire valve to size
Once the combined diameter of the tape and the valve tube is the same (pretty tight) as the hole, it's enough.
Step 6: Assemble and Check Fits
You may have to really squeeze the taped end into the hole.
Then, put that whole thing on top of the bottom (yeah, confusing?) of the can.
If everything looks like the picture, you're ready to move on to the gluing.
If not, look back at the other steps.
Step 7: Apply Glue
Take an about 1/2" sized (just an estimate) bead of glue - PL Premium Adhesive if you're using it - and spread it along the what's left of the bottom of the can - the doughnut, not on the inside. (refer to the first picture)
What you're going to do is put the endcap assembly on the bottom of the can like you did in the previous step, so apply the glue in that area.
Take the valve out of the endcap from the previous step, and smear glue evenly along the 'top' side of the bulge (the side closer to the valve cap). Also, spread glue along the full area of the circumference of the electrical tape that was wound in Step 5.
Re-insert the valve into the endcap the way you did before.
With the endcap assembly (including the valve), you'll want to smear another bead of glue - slightly larger than the first - all around the sides of the valve bulge and around the surface formed by the pipe and endcap. This is shown in the second picture.
Step 8: Assemble Permanently
When everything is in place, smear more glue along the seams; make sure there are absolutely NO cracks or gaps.
Step 9: Attach Rubberbands and Let Dry
Take one of the rubber bands and wrap it around one side of the valve, and take the other end of the rubber band and twist it once. Then, stretch it down to the spray button on the can and hook it around that. Do the same with the other rubber band, in the other direction.
Sorry if this is not clear... it's all a little hard to explain, but I hope the pictures help out. :D
And finally, the hardest part - let it dry for a full 24 hours.
Step 10: Pump it Up!
Pump it up until the gauge reads about 35-40 PSI. You probably shouldn't pressurize it more than 50 PSI.
Check for leaks. If there are any, it might work if you seal it up with more PL Premium (I don't know for sure if this will help) and let it dry.
Detach the air-osol can. (Yay, you can finally call it that!)
Spray to your heart's content (or until the air runs out)!!
Step 11: Possible Uses
However, one thing that kind of works is opening the valve by pushing the plastic tube thing down with your fingernal, and then running water into the hole (it's going to flow over and around it, too) until you can feel water in the can. Then, you pump it and spray.
EDIT (thanks electro!): You can get a simple tool that will unscrew the centre (the little steel plunger) of the tyre valve you fitted on the bottom. You then invert the can, pour in the contents, replace the valve core, pressurise and go!!
Also, just a concept, you might be able to feed butane/propane/alcohol into the plastic tip by pushing it down (thus opening the valve) (EDIT: or utilizing electro's idea) and squirting your fuel into the can, and then pumping it, but I haven't tried this.
Experiment, and have fun! :D
If you have more ideas, please comment and I'll add them to this instructable.
EDIT (thanks pineapplenewton!): Use it as an air duster!