You need a laser printer, packing tape, and a couple of minutes.
This will not work with ink jets, only thermal toner, or indelible ink based products.
Step 1: Make some designs and print them !
The white (paper) is removed later so it is clear.
I have found that the worst quality paper makes the best decals.
This only works with thermal - non water soluble printers like a laser printer.
Most copy machines use thermal ink.
Step 2: Cover with tape and press it down...hard!
We need the tape to stick to the color particles.
Rub it down firmly...
I used the flat end of a battery on a hard surface.
After pressing the tape down, trim the decal near the margins.
Note: Where printing covers the surface there will be little glue left to stick to the surface.
If you have a lot of printed area, leave extra border.
Step 3: Soak it, rub it, dry it....
Get a piece of wax paper ready.
Rub the wet paper on the tape. It will start to come off of the tape.
Keep everything wet. We are not removing the glue just 95% of the paper.
The paper will come off but the image will remain.
When done lay decal on wax paper, sticky side down.
Do not press the decal into the wax!.
Step 4: Apply the decal to the rocket tube
Good luck, and happy decorating.