dont waste your valuable time,buy a smoke pro,had mine about a year,seems alot of money for something you think youre not going to use,however its gets used now most days,as u know the modern car has so many vac pipes & valves we cant possibly pick out a small leak without it,worth every penny,if your hourly rate is £40 a couple of hours a week wasted trying to find a small vac leak soon adds up!ps you have to have the machine turned well down to establish small leaks too much smoke is not good,dont think you could regulate a homemade properly,just my thoughts,keith.