AquaSeal Adhesive comes in a tube and can be found at many dive shops.  You
can use it with Cotol-240 to cure faster.  Both these products will become
useless in short order without proper storage.  I'll tell you how to keep
them in useful condition and what they are useful for.

Scuba gear wears out over time.  Some just falls apart while some wears,
gets torn, or otherwise takes a sh.t.  My wetsuit (ScubaPro) fell apart.
The stitching let loose leaving me with big gaping holes.  Solution:  Sew
the seams with needle and thread, clean them with Cotol and cover them with
AquaSeal.  If you mix the AquaSeal with Cotol the AquaSeal will cure faster.
AquaSeal seems to run somewhat in either situation so you need to be careful
with how much you apply at one time.  After a few days of sewing and pasting
my wetsuit was like new.  Actually, better than new because the stitching
can't come undone and the seam is impervious.

Ice cap repair.  The ice cap is molded and has a seam in the center from
front to back.  Over the years the seam let loose and there was some ripping
of the cap material.  A couple stitches with the thread to hold the seam
together then a paste along the seam or tear with AquaSeal and, poof, good
as new.

Drysuit leaks.  I use the ring system from OS Systems.  This system
stretches the wrist seals over the outside of the plastic ring.  Any small
stones behind the ring or hitting the ring against something hard will
create a pin size hole that will leak when diving.  I was sick of looking
for the last hole so I used the rest of the tube to paint the area on both
wrist seals.  I still have duck tape threads and adhesive from a few years
ago when I fixed the problem with duck tape.  The Cotol would not cut the
adhesive and remove it but the AquaSeal seems to work over the duck tape
adhesive; although I wouldn't recommend this type application.

Over the years I've bought AquaSeal and Cotol only to find that when I go to
use it the Cotol has evaporated and the AquaSeal is hard as a rock in the
sealed tube.  I've now kept the products for over two years without loss by
keeping them in a Tupperware container in the freezer.

That's about $300 in savings for not buying a new wetsuit and more comfort
when using the existing equipment.  I'm currently out of AquaSeal and
Cotol-240.