It was too nice a day to stay home and work!
Yea, a hair dryer will work alltough slow. It can be improved a bit by using a difuser like a funnel to concentrate the air flow and changes the rate of air flow. This make it work harder and it heats it up more. Be careful not to burn it out. Some are more sensitive to it than others. So don't use the wifes good hair dryer or you'll hear about it the REST-OF YOUR-LIFE! Trust me on that one.!

I had one of the Harbor Freight heat guns and it lasted about a month.
The Shop Hair Dryer has been hard at it for 15 years. (My old HD from when I had long hair)
A shop heater works well to, or a butane torch ot lighter. But you have to be careful not to burn the tubing or bungee cord cause the get way to hot.
Ace Harware, Wally World Automotive and most Automotive stores sell heat shring tubing.