I've done this kind of thing many times. Working on something late at night, I made a stubby wrench out of a regular wrench, a crows foot wrench out of a box wrench, I made a O2 sensor socket out of a perfectly good deep socket. When you got the tools and the will, it's amazing what you can do.
BMW sells this special thin 22mm wrench to keep the fan clutch from turning while removing the fan, it was like $85 AND SPECIAL ORDER. I made one out of 1/8" flat steel, cut it out with my oxy/acetylene torch. It aint pretty but its in my tool box for the next time.
Given the choice I'd rather go out and buy what i need, but sometimes, It's too expensive, Or I'm in a pinch and I gotta getter done.