Hi!
I don´t know how it´s in your area, but here in Finland 3M sells that "glue" (atleast that permanent one) in their shops. It´s not in cans or tubes, but it´s thin glue layer between two covering papers. Like that mounting pad, but without pad. Just glue. When I bought that it was about one meter wide roll and they cut as much I needed. Very sticky stuff
Check 3m web site and look what is your nearest reseller and ask do they have different kinds of that.
Hope this helps.