As someone above mentioned, I've also used Dupont "Imron Industrial Low VOC" (there are many types of Imron... I use the Industrial low VOC one). I bought mine at Finishmaster. I chose this paint after a ton of research and talking to a friend who showed me all of the machines he used this paint on, which look brand new despite lots of use and exposure to the elements.
This paint can be brushed on if you have them mix it specifically for brushing. I have not tried this, but a friend has with good results. It's also apparently way, way safer in terms of exposing you to isocyanates versus spraying.
2 protips:
1. Any 'good' paint like this has isocyanate in it. This stuff will kill your nervous system and you will die if you breathe/ingest it. Seriously -- this is a whole new level of poisonous compared to most other poisonous things you have dealt with. You are supposed to only spray it with a full body suit, nitrile gloves, and supplied air (think SCUBA). I personally sprayed my machine with a full body suit, nitrile gloves, and an organic charcoal filter from 3M. The danger with this is that, when the filter gets used up you start breathing poison, which does not have a scent. The point is, know the risks and do your research before you try any isocyanate paint.