Doug gives a very good if short description of the process. The big factor, IMO, with painting is balancing the expectations with the abilities/budget. I have had Doug paint a few of my bikes (and I will say he was painting as I did all the sanding and prep) because I do want the best looking result and also have good durability. The two part paints he usually uses (HoK and the beloved Imron) can have a deep luster and the chemical curing hardens the paint so chipping is less than single component paints can attain.

The tooling costs are high for this method though. Air compressors (and the electrical service capacity), air lines and oil filters, spray guns and cleaning products can be more than a few hundreds of $. The paint, it's hardener and primer won't be cheap and likely will only be available in quantities suitable for a dozen bikes. Then there's the practice time and consumables to get comfy enough to try an actual frame.

The far more common way newbie/home painting is done is with spray can paints. These paints and primers are available in single component low cost versions (like Rust-Oleum) or two part paints (the can has the two components separated by a barrier which one breaks and then shakes the mix up before spraying) more often found in the automotive paint supply stores. Without a doubt these two part paints are more durable than the cheap single part paints but a single can costs 2-3 times what the cheap stuff does and the working time of the now mixed with the hardener paint is limited. For a best job with these paints/primers figure on needing a can+ per layer. Count the layers and do the math.

As Doug mentions "painting" is really far more about the prep than the tooling or materials. To get the results you see proudly shown here and on line takes a lot of time. When Doug has painted my frames we took a week working near full time on them each. A pro will reduce this time as they are far more efficient as the prep work than I am. A total newbie would likely take longer than I do. The actual time in his spray booth for all the coats was less then 2 hours over the week.

(Although one aspect of the "how long to make a ..." is that one gets better at seeing stuff sooner than one gets better at doing the work, early on. I kept track of my hours to make a frame early on, at around 25 hours (before paint). Now 45 years later I take 2-3x longer as my skills of making my job easier are not as refined as my ability to see how the brazing/mitering/finishing looks. This is one of the reasons why I have never hung out my shingle). Andy