dude DONT DO IT!!.. at least not from a 40 watt bulb.. you wanna go 60 or higher...

you could still use the 40 watt bulb but your likely to have a hot peice of glass get shot into arm... (well thats what happened to me).. be careful useing lightbulb vapes make sure you dont touch them when you've been useing them.. (yup stuck my hand on one of those fuckers too) and most importantly when you've made one from a higher wattage bulb dont put it in your pocket and walk down steps ( did that too glass in the leg fuckin kills !!)