WARNING : the following instructable deals with UV lights. This is dangerous for the eyes and skin. Protect yourself with appropriate gear, and don't let kids PLAY with it, as you wouldn't for your car or explosives. It is not a toy.

A while ago, I worked on a project for school (graphic design school), and the brief was to make a low-cost (like in "not expensive" not like in "crappy") identity, and way to print stationery and honey jar tags. I chose stamps as a way of printing because it would allow my client to print his stuff at home. So I looked around on the web, about companies that make stamps. Problems were that the size choices were limited, and the prices were often very high. I then realized it would probably be easier making my own stamps. Once again with an array of problems, like the price of the machine (just a damn UV light box ! ). So I took on making my own UVbox.

I realize it may have cost more than actually buying the real thing in the first place -because of all the failings and the waste of material- but at the time I was excited about making it.

It would have still been cheaper than the real deal without all this trial and error. So here it is. First instructable, hope you enjoy.

Step 1: Materials

Tools
- a wire cutter
- a box cutter
- a flat screw driver, the electrician type, but really any small flat screwdriver will do
- a pair of scissors

Materials
- some reflective material, like mylar (aluminum could do, but it's conductive, so be careful to isolate)
- some cardboard
- two paired luster connectors (these are cheap, yay!)
- some 2mm wire (2 colors if you want to do it clean)
- 1 220/230 plug
- 2 G23 9W UV lamps
- 2 G23 sockets 5/9/12W WITH BALLAST
- photosensitive gel available for a decent price at the source
- a cardboard box ideally between 17cm and 20cm high (~ 6-8 inches)
- some adhesive tape
- some electrical tape
- glue that glues !! I use contact glue. Yellow stuff, pretty disgusting and stinky, but helluva lot sticky
- 2 glass plates (I scavenged them from picture frames)
- some small drawing clamps

- transparent printable rhodoïd
- a printer

Optional
- a 220V switch

For the lamps, I first bought a very expensive powerful UV bulb, nicely warped in protective paper. It snapped as soon as I turned it on, so prefer the tube or U shaped ones. You'll need a ballast (as far as I understand, it's a kind of starter, gives the necessary impulse for the gas to start emitting light and then limits the amount of current going through the tube - pretty neat if you ask me) for them, but the total is still cheaper than the bulb alone.

Step 2: The Light Box

Once you have gathered all your component, let's start.

The instruction to wire the ballast were provided with my order. But in case you don't have them provided, here you go. It's pretty straightforward, basically a wire in each lefthand hole. One goes to the neutral, the other one to the phase. I don't think it is polarized, so it doesn't really matter if you invert them. But if you do invert them, make sure the wiring is the same on the other ballast. Not sure what it would cause, probably not much, but hey, dealing with 220V here. Better not screw up.

Once you have your two ballast properly wired, you can link the two with the luster connectors, as shown in the picture.
Then hook that up to your 220/230V plug. Put the lamps in their sockets, and you have a working UV lamp !!

Step 3: Building the Reflector (optional)

I didn't really experiment without the reflector at all, but I don't see how it could make the project go wrong. So it's up to you to make one or not. You probably won't have the same timing of exposure without it or if you build it differently.

Unfortunately, I don't have picture of the whole building process, but basically, you want a curved base to glue your mylar on. It has to be big enough to let the ballast go underneath it, but the bulbs/tubes on top of it.

The wiring in the picture is NOT what you want. This was just a test phase, and I did it a lot cleaner in the final version :)

I then boxed the whole thing and added a WARNING tag

Step 4: Now the Fun Part : Stampmaking

Now that you have your UV lightbox, what to do with it?

Well, not so much for now, because we need to set some things up before actually burning matter with light.

First, what will you stamp?
you need a logo / text / drawing to put on your stamp.
Whatever you chose, you'll need a black and white inverted image of your image. Basically, what you want stamped, needs to be white, what you want NOT printed has to be black. The whole thing has to be inverted, because stamping will inevitably invert your picture again. (right will be left and vice versa)

The picture pretty much speaks for itself. Step1 is your design. You need to invert it, and invert the black and white areas.
Step3 will be printed on transparent rhodoïd.

Second, now you have your design
printed on transparent rhodoïd, you need to take a sac of gel, put your design on it, and clamp the whole thing between glass plates. I found that the more clamps, the better. This is because the gel is thick enough, and won't lay flat (really flat) if you use only 3 or 4 clamps. The pressure should be equal all around the apparatus.

Step 5: Expose to Your Newly Created Mini-Sun

OK, once again, wear appropriate gear. This stuff probably won't make you blind (unless you look at it for an hour or so) but is still pretty aggressive. I wore good sunglasses during my experimentations, and still felt some irritation in my eyes. Also cover your skin.

That said, let's go on with the instructable.

What you need now is the cardboard box, and gently place your glass / design / gel / glass sandwich in it. Then the light-box complex on top of it. Do not turn the lights on yet, make sure your design is backward, and that the sandwich is in the area where there will be the most UV light striking.

The distance of 19cm is what I found best to avoid indirect exposure from the side of the sandwich.

Now you're all set up, put your shades on, and turn the sun on! for 4min and 45sec. If you can, avoid being in the same room, as a precaution.

After this time, you can expose the back of the sandwich for about half a minute to give the stamp a base.

Step 6: Almost There

After opening the glass sandwich, your rubber stamp is almost ready. It should look like the first picture, and you should be able to see it inside his sac of gel. Now we need to get rid of all that unsolidified gel.

This should happen over a sink, the gel is pretty sticky, and probably a bit irritating for the skin. Again, wear appropriate gear.

Cut open the sac on three sides, so you can access your stamp. Take it out and dump the sac.

Now rinse the remaining gel, and scrub gently with dish soap to remove all the left over.

Once clean, put it back on a glass plate, and in your UV-oven for a 15 to 20 min hardening in the artificial sunlight.

Step 7: Mounting the Stamps

Now you have a rubber stamp, you probably realized it's gonna be difficult to do anything interesting with it, unless it lays on a hard surface. Well, this step is pretty straightforward : let's glue the rubber stamp on a hard surface.

The final presentation is visible here