After 45 years in the trade, I had one of the trickiest jobs I’ve ever had. I had to fit a ribbed, stretch alternator belt to a Focus with a double crank pulley! Took me bloody ages! I normally just wind them on like a bike chain, never needed a tool but the angle made it impossible, even with three of us on it - one turning the crank and the others trying to keep the belt on the pulleys. I bought a universal plastic belt tool from Halfords which shattered when I tried to use it. Ended up spending a fortune and waiting for delivery for a tool that bolts on to water pump pulley and can only be used on that engine! Air conditioning belt slipped on in 20 seconds.