Drilling through Details West Castings

NWR #200

Irish Expatriate
AI just picked up a pack of Details West Gyralight cvastings at my LHS. I want to make these working models and so picked up some bulbs for them. Does anyone know how I should drill through the castings to make holes for the bulbs?
When I do stuff like this, I usually hold the part being drilled in my left hand, pin vise in the right hand. It doesn't take too much pressure to get the bit to cut into plastic or white metal castings, provided you have a sharp bit. But, a vise would be best, certainly a lot safer...