Here's my friend's and my instructable on how to paint a spud gun.

Step 1: Materials.

>Prep stuff
-Sandpaper
-Mineral spirits
-Rag
-Orbital sander (helps)
>Painting stuff
-Spray paint (depends on design)
we needed
-Krylon Fusion Red
-White Rustoleum
-Krylon Fusion Orange
-Blue Rustoleum
-Clear coat rustoleum
(rustoleum we had lying around)

Step 2: Prep: the Most Important Step

Time for prep. The single most important step of any paint job.

We started with 2 finished guns. We based our design mostly on the Nightlighter 36 in Make Vol. 3.
The basic design of that gun being:
18'' of 3'' PVC for the combustion chamber
36'' of 2'' PVC for the barrel
2 bolts through the sides of the combustion chamber, stun gun used to ignite the fuel.

We changed the design by using 4'' PVC for the combustion chamber instead of 3''
And using a scavenged spark igniter off of a grill instead of a stun gun (we couldn't afford to spend the $20 on stun guns, tight budget)

Step 3: Removing Labels.

First off, you have to remove those icky labels. They can't stay there for painting.

You won't be able to get it all off by scraping, you have to use a solvent.

Two major household ones; Naptha (aka lighter fluid) and Mineral Spirits.

To use it: Just put it on a rag and rub, it'll come off in no time!

Step 4: Sanding!

paint won't stick to an excessively smooth surface. not will it look good on an excessively rough surface.

To sharpen the barrel, 60 grit on an orbital sander was used (fastest way to take off material). trying to put an edge on the top of the barrel to make it easy to cut a potato

Then 150 grit sandpaper was used to try and get out those nasty nasty marks from the 60.

400 grit sandpaper was used all across the gun to make an optimal surface for paint to stick to.

Step 5: A Good Painting Setup.

A good painting setup is probably one of the most important parts of getting it right. You want to be able to cover the ENTIRE surface at one given time.

We used 2 saw horses and 2 poles, stuck the poles through the gun, and put them on the saw horses. All held together with friction, worked perfectly.

I've heard of other people using old tables, flipping them upside down, and putting the spud gun on a leg of the table.

Since the cleanout cap has to be painted seperately, that leaves both the barrel and the combustion chamber open, we can't let paint get in there...but how?

We solved that problem by rolling up newspaper and just shoving that inside the barrel and the combustion chamber. We also put a strip of painters tape on the beginning of the barrel and combustion chamber, just in case any paint DID get there (due to a slight gap between the newspaper and PVC in some spots). So it wouldn't be a pain to remove or gum up the threads.

Once finished, there was no paint in the combustion chamber/barrel. This method was a great success.

Step 6: The Base Color

The first color we did was white. Two coats were required to cover up all the black writing on the PVC from the manufacturer.

We ended up using some fast drying interior/exterior Rust-Oleum white spray paint i had lying around. Worked like a charm.

Step 7: Design/taping

We just did our design with tape, we went for something basic. We wanted a bordered square pattern on the main PVC section of our combustion chamber.

We had thought about doing the same for the barrel, but we realized that it would most likely look bad, or have too many small squares. We ended just going with a stripe pattern for the barrel. Turned out VERY nicely.

Step 8: Second Color

Now that the design is down, time to get painting that second color!

We used a nice Red Krylon Fusion paint. Another 2 coats applied here.

Step 9: The (second) Best Part!

Time to remove the tape and...see your paint job!

It looks great? Right?

Well...you're not out of the woods yet...

Step 10: Last Time You Pick Up That Can!

Time to protect that wonderous paint job you just made.

Time to clear coat.

We applied two coats of clear coat, protecting it, and making it shine more! (that krylon red already did quite well)

Step 11: Enjoy!

Well..look at that BEAUTIFUL paint job you just made!

Time to enjoy your new....shelf queen?

You don't wanna ruin that AMAZING paint job with potato gunk and right guard...do you?

Step 12: Well. I Said I'd Get Back to It.

Okay. Well, wonder why you saw 2 spud guns at the start, and only one at the end.

We were going to do the guns one a time, learn from our mistakes. But one was made that sort of hindered that process

Whilst moving the gun alone out for clearcoating, i accidentally knocked over the other gun, and it hit the concrete floor and the 4''-3'' reducer was cracked

This instructable will be updated with the results of the second gun once it's repaired and painted