I am lucky to have a very good powder coater in my area, PPS Glass Fibre of Inverurie - https://www.ppsglassfibre.co.uk/
I have used them to powder coat the frames and ancilliary bits and pieces of my AMC and Triumph restorations. They're very helpful, blast in house and will apply a three coat finish, (corrosion inhibitor, colour and clear coats), for what I consider to be a very reasonable price, (particularly when compared to a professional paint finish).
I have been so impressed with the finish and it's cost that I decided to bite the bullet and try powder coating on the bodywork of my Ariel restoration, unfortunately the blasting process revealed some minor dings in the fuel tank that I was unaware of. Luckily PPS didn't go ahead and coat the tank and I collected it to consider my options:
Knock out the dings - I don't have the level of tin bashing skill to perform this and am not keen on slicing the bottom off of the tank to allow access. It would also add substantial cost to the project.
Fill the dings and spray the tank - I can do this at home, I have successfully matched the finish in spray paint to allow me to paint the rear dampers. Downside is that the finish would differ from the rest of the bike and may be 'obvious', cost of filler, primer, under, top and clear coats Estimated at around £75.
Find a filler medium that would be compatible with the powder coating process.
I decided to have a go at the latter:
Whilst at PPS I bumped into the chap who does all of their powder coating and asked him if he knew of a filler which could be powder coated. He told me that there was a readily available purpose made filler that worked well with powder coat and on his recommendation I bought some of this:
Here are some of the dings in the fuel tank revealed during blasting:
And the result: