Ok, here is something my friends use that may not work for others.
Punch a hole ( with a nail ) at the top edge of the cap/lid, tilt the can and load the glue with a half inch flat brush. The brush will be harden like a piece of wood but shaped like a chisel and that's what the idea is all about, hard and yet flexible.
As for me, I use a plastic bottle, drill a hole on the plastic cap. For small project I squeeze the glue on my finger and for larger piece, I use the cap as a spreader as I squeeze rather than many had mentioned using plastic cards. Place a scrap piece of leather over the hole after use.