Help with Duct Tape patterns

I'm brand new to the LJ community (literally about 20 minutes new)so I apologize if this post isn't in the right area.

Anyway, I'm having issues with the tape patterns for my heads. I've been using packaging tape instead of duct tape and I can not get a straight line when I cut it off and it makes the patterns very choppy and hard to see the edge especially down towards the neck line.

Should normal duct tape be used instead? If so, will this rip out chunks of foam?

Thank you for all the help and for convincing me to get an account here!