For large mounts, it would be nice to have a fixture. When I use the glue pen, I do not use a continuous bead but lay down small amount then move across say 3 mm to put down a little more. The challenge for me is holding them since one hand has the pen.
A spot seal, that's a fine idea. I'll do that. The soldering iron was in the original post and using it with my old hands concerned me a bit. Thanks for letting me know what materials the Hawid pen will seal.