I live in the city of the silk, Como, and I lived near a photoengraving lab for some months (then the lab closed), so I always saw here and there fabric printing works.

I did it with stencils (too long and I don't like it) and felt tips (but this technique needs really good drawing skills).

So I've found the nitrocellulose thinner method!

Please, vote for this 'ible in the contests, if you like it :)

Step 1: Materials

A T-Shirt, a bag, fabric.... anything you want to print, possible in cotton
nitrocellulose thinner
a fork or a spoon that you won't use to eat
a little flat brush (it doesn't need to be a good one, the one you buy at 1 $ store 10 in a package)
a flat piece of wood or cardboard
pins
adesive tape
laser printer
image editor (MS Paint, Paint.net, or Irfan View are ok)
flatiron
mild soap (optional, but racomended)
fantasy :)

It's important that you do this in a well aired room, because of the gas of nitrocellulose thinner.

Step 2: Fantasy

Choose the image or the sentence you want to put on the T-shirt.

Keep in mind that it will be printed on the T-shirt backwards, like it was in a mirror. This is important if you are printing words, or drawings that have a direction.... for example a car or the photo of your cat, if he/she's like my kitten Enya, that is wonderfully asymmetric.

So, if you choose an image, just flip it horizontally with the image editor you use (Irfan View shortcut: H).

If you choose words, copy the screen, paste it in Irfan View, cut the part you want to print and flip it.

In the example I've put words and a drawing (F'Ral, a character from my star Trek: Enterprise fanfictions ;D). The drawing is a too pale, try to use dark prints.

Step 3: Prepare the T-shirt

Iron the T-shirt. Put it over the board. Block it with pins and/or adesive tape.

Step 4: Print

Print the image/words you want to transfer and place it face down on the T-shirt. Block it with tape and/or pins.

The sentence I chose for my T-shirt says (in Italian):

There are 10 types of people in the world: who knows binary code and who doesn't know it.

Step 5:

With the brush, rub the nitrocellulose thinner on the paper. The drawing/words will appear (right side!).

Step 6: Fork/spoon

Rub the paper with the fork or spoon. Press down a bit. This will help the toner to pass from the paper to the fabric.

Step 7: Yeah!

Take away the paper and look at the magic!

Step 8: Iron

Iron it with the temperature as high as possible for the fabric (this is why cotton is better).

Step 9: Repeat

Repeat with all the prints you want :)

Wash it with mild soap and lukewarm water.

Step 10: Free Your Fantasy!

I like reusable bags, I've got some advertising fabric bag, so I printed on a piece of fabric some images and words from some of my favourite TV shows (Star Tre: Enterprise; The X-Files; Breaking Bad) and sewed them to the bags.

For now I didn't try with laser colour printer, because I don't have one, nor with a ink jet printer. If you do it, please let me know the results!

After printing the fabric with this, you can colour the image with fabric paint or felt tips :)