I cleared out some space in the shop, which happened to coincide with one of the few slider windows.
I then re-assembed an old server rack I had laying around. I have a lot of junk.
It's not very big (a tad over 26" square), but large enough for small parts.
The main steel shelf is at counter level, one is at the top of the rack, with a few others under the main shelf. Over the top shelf is an infrared heat that acts to heat up the whole shelf as an indirect heater.
On the inside are a few thin particle board walls. The back wall has a small fan, hooked to a powered electrical box. The side walls feature two flood light sockets, each fastened to junction boxes.
Between the flood lights (moderate heat) and the infrared (lots of heat) I can decide to pre-heat or post-heat items.
A lazy Susan turntable is a really good way to get a good finish on all sides -- hold the spray can in one place and turn the item to be painted. I also have a wire rack on top of the turntable for larger or multiple items.
The total cost was $17 for the small fan, as I had everything else just laying around.
Took a few hours to screw together and get it close, another few hours to wire and install the switches and fan.
Just pre-heat the part, slide the window open, turn on the fan and spray!
Pic of unit (click once to expand; click "box arrow" to zoom):
With lights on(click once to expand; click "box arrow" to zoom):
Build your own out of plywood or an old cabinet.
For extra credit, what am I painting?