I have sprayed my frame with rattle cans. I am not really bothered about a perfect finish.

If you use primer it can be applied much thicker that colour without dripping. You need to spray the colour on a lot thiner or it will drip, this has caught me out where I sprayed the colour on like I did the primer and got drips

I used a lot of clear coat as well.

One think to think about is drying time, the more time you can invest in painting so you can do more thiner coats the better.
Also the more time you can leave the paint to dry the better. Mine took a few months for the paint to reach full hardness.
If you can spare the frame for a week or two hang it somewhere warm. This will hopefully avoid any damage when building. When the paint is fresh even tiny stones will damage it.