Reddit reviews Hold Heet Electric Glue Pot, 1 Quart

You'll need a warmer for it, because it's solid at room temperature! And be warned—it SMELLS. It's literally melted animal parts, and it smells like it.

ETA: We had this one at the shop where I was learning violin making, but it's pretty expensive to invest in on a whim. I've also read about people using crock pots; YMMV. You want to use a glue like this, not the weird shit that comes in a bottle pre-made. And seriously, it stinks. Don't do it in a room that you want to smell right ever again.