Yo Sage

Gotta keep that blood flowing! I have cut the neck seal on my dry suit to fit twice now (first time it was new and then I had it replaced after a couple years of thrashing). Each time I was as nervous as you and I would be cutting out a hatch in a strip plank kayak.

My neck seal had a series of rings which were a good guide to keeping the cut 'straight'. First time I ended up with a little nick that made me nervous every time I used the suit, but survived the life of the neck seal. But it is better on the nerves to have no nicks. So you will be wanting the best, sharpest pair of scissors you can lay your hands on.

In my case it was a matter of cutting a ring at a time (3mm/1/8") and trying it on for size.

I use plenty of baby powder to help slip the dry suit seals on and off (Other people use liquid soap which foams in a disturbingly rabid fashion. Another favourite is KY jelly - I'm too nervous to go order a bucket of the stuff from the chemist and have an irrational fear of the stuff gooing up my under drysuit garb, but apparently this is the lubricant of choice for drysuits and works for putting a wet one on too) what you use depends on your personality, I guess ?

Another on going debate is whether to have the neck seal straight or tuck the top inside itself in a little roll. I am a tucker and this arguably can make the difference between a dry drysuit and an annoying leaking one (but the roll has to be continous around the whole neck, a half roll/twist = a leak for sure). So You have to decide whether you are a roller or not. I guess a roller will be cut down a shade less than a straight-er.

At the end you want it leak proof which will be about mildly uncomfortable but won't leave you gagging/with permanent red/blue rings on your neck afterwards/ and definately no love bites after 5 minutes.

Good luck and cut conservatively

Pete