Hi again Ed. To be honest, for small lights in small scales, if the lens is supposed to be coloured, rather than clear, I just paint them, then give them a coat of gloss clear varnish, or sometimes a thin layer of PVA, or the expensive version, Micro Kristal Kleer.
Regarding the paintings, I paint in oils on canvas, using brushes, very occassionally the edge of a small pallette knife, and my fingers - if neccesary. The texture of the canvas, and various techniques, mean that an airbrush isn't neccessary, and probably wouldn't be an advantage anyway. I do, however, occasionally use an airbrush if I paint a profile or similar. In a way, the picture painting has helped me with the modelling, and vice versa. I've been doing both since I was around 8 or 9 years old, the pictures since about 5 years old, I suppose (although 'kiddy quality' then, of course!), and I'll be 58 next month, so both have grown together, in a way. Like most of us, I had various breaks from modelling, due to the military, the civilian pressure of work, marriages, kids etc, but about 25 years or more ago, I started to use models as the 'model' for my paintings, in order to achieve perspective, the right lighting and depth etc. Rather than just throw the kits together to obtain the shape and form, I decided that, if I was to build the model, it might as well be done properly, and be a piece of 'art', so to speak, in it's own right. Consequently, I've run out of room a number of times over the past few years, and had to give away models (most are 1/48th and 1/32nd scales), although I do offer to provide a scale model of the subject, to accompany the painting, if a client so desires. Works well - I get the use of the model to help in the painting, and the enjoyment of building it etc, then get paid for it with the sale alongside the picture!