Very simple I believe I just showed this to someone else recently
What I do is take a piece of metal stud which you can get in Home Depot, in fact I use a couple of them if I am doing alot of tubes. I used threaded rod cut up in pieces but you could use anything. You could use bolts, metal drywall screws or the like as long as it is metal. I screw them into the metal stud and stagger them back and forth so that when spraying I can get around each one with no problem. I slide the tube over the bolt and then take small piece of tin foil and wrap around the extended bolt and it slips into the top of the tube ever so slightly just to block the tube from overspray. Do not want that inside the tube. I use tin foil on the bottom also. You can reuse these as many times as you would like. Have been using mine for a few years now when I was using them. I use to do all my bullet casings this way when I made the cartridge pens at one time. I sprayed them with clear.
I did not use a nut and washer at the top because it will become part of the tube and be hard to get off especially if the threads were sprayed. Plus it may crack the coating. Very easy to take the thin tin foil off without problems. You can also use silicon corks for the tops too.
I then spray away and take metal stud and put in my oven that I bought on clearance at Walmart for practically nothing. It was dented and returned. Set timer and good to go. Works very well. You can set this up to do as many as you can fit in oven. By doing this no shaking where the product falls off the tube before baked. Just a warning, if doing 2 part kits keep some kind of record to identify tubes later. Belive me you will not regret it.


I should specify, the jig on the left is for tubes and the one on the right was for bullet pens when I was clear coating thus the need for poprivets which were thin to go into the bullet easier.
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