Rubber Fuel Lines Are Dangerous

My main fuel lines (feed and return) are nylon12 EFI tubing and turn up following the firewall to the top of the inner fender, then turn over to the carb to keep it all away from the motor.

I've used Nyon12 in shorter lengths on other projects but was planning to run both pressure and return for the whole car. How did you form the tubing? Heat gun?