Here is a little instructable about making waterproof stencils from recycled plastic or more precisely HDPE Milk/Water Jugs. I have seen some awesome stencil "Ibles" on here like the ones using freezer paper for floating islands (Should really search the site first before I start making my own Ibles) but I feel I have a unique twist to add RE: the stencil medium and recycling factor. So let's get started!
Step 1: Assembling the Materials Required
You will need:
A Sharp blade (I used a box blade although I suggest perhaps an exacto)
Masking tape (you can use just about any kind. It's all about what you would wanna pull off your monitor screen really)
A writing Utensil (G2s are great for definition,a non bleeding sharpie would be better but a pencil would give you the most precision IMO)
A milk jug (Or any thin clearish plastic would do. We are looking for what I call "real estate". A flat area in which to cut out the stencil. I use Milk/water jugs because it's what I have and I love the idea of being able to recycle.)
A flat monitor connected to a computer (Alternately a touch screen smart phone or tablet can be used for small stencils. Also I suppose a CRT "fat back" type monitor could work as well if you find a way to use the screen as a backlight, an idea I had was to make a sturdy wooden box then a square cut large enough to sit the "fat back" end in but still hold it steady for tracing)
A cutting surface ( I used an old box)
Step 2: Find Your Image
Find the image you want to use. You can google image search, like I did, or make one using special software and a base image you want to "stencilify". For this one I chose (edit: my wife chose) Princess Peach and a Mushroom.
*Tips Using google image search In firefox I suggest you right click the image and click view image without going to the host website then you can press CTRL and + or CTRL and - simultaneously to resize the picture you have selected. Also you can press the F11 key to view in fullscreen mode.
Step 3: The Trace
The idea here is to use your monitor as a light box. What I did was move my mouse and keyboard aside and pull my monitor down onto my desk letting the stand part hang off the edge. Afterwards you can apply your paper and tape the corners of your screen so it doesn't move around while you are tracing.
Taping on your screen is why I suggest masking tape. I would kick myself for letting a sticky residue mess up a $200 monitor also when you trace I don't suggest you press down very hard with your pen or let your arms/hands press into your screen very hard. Some monitors especially laptop screens are very sensitive to screen burns,dead pixels and scratches. Use caution and as a disclaimer I am not responsible for any damage you do to your monitor/screen or self while following this instructable.
*Tip I find that being right handed at times my pen gets in the way of seeing the trace line so when possible I try to trace from right to left. This could be reversed if you were south paw.
Step 4: Getting Ready for the Cut
After you have successfully traced your image onto the paper you will need to find that "real estate" I was talking about. I did this by trimming the excess paper from my traced image and placed the image on different sides of the jug until I found a relatively flat spot that it fit. I used a largish image so finding a flat spot to cut out on the jug was a bit difficult. Even then I had to trim the jug down as much as possible in attempt to flatten the surface and remove the curve of the jug. I suggest finding the area first then choosing an image of appropriate size to trace, but hindsight's 20/20 I guess.
Now that you have cut out the piece of plastic you will be using place the image underneath the plastic and tape the back of the image to the plastic. This will minimize the movement of the paper and the possibility of tearing while you are cutting out the stencil.
Step 5: Cutting Out the Stencil
The devil is in the details. This is the part you want to be very careful with your blade. One slip could result in a messed up stencil or worse a messed up hand. (Again not responsible, do this at your own risk) You can either pop out the cut lines as you go or after your done. I do it as I go so the cut lines don't slip out underneath the plastic and make it hard to follow straight lines with the blade.
*Tips The same as with the trace I find it's easier to see going right to left also when cutting small details and sharp curves turning the whole image as you cut makes that process a bit smoother
Step 6: The Finished Product
Well here it is my Princess Peach and Mushroom Stencils (got a lil' impatient on the 'shroom) Time to test it out!
Step 7: Testing
Looks good to me! You can use the stencil for spray paint as I did. My wife also did some other stuff showing other ways to use it, like tracing with a sharpie then using markers or coloring them with regular paints. Let me know what ya think :)