There are some suggestions in this thread:
Embossing/Stencil paste
In there, I mention a Winnipeg arts supply store which also has an online store...and someone in there mentions what we can use
acrylic molding paste, which is found at arts supply stores and probably Michaels.
Else, try PM'ing Topaz (the person who made that thread) as she's also Canadian and recently found some.
I hope this helps!