We are trying to make microwave hot packs, any ideas fo Sewing Machines Parts and Sales in Los Angeles

Making a ton of these for birthdays and christmas, and one of the most time consuming things is pinning the grain inside the pocket.

We cant use 2 magnets to form a seal, as the magnets mess up the sewing machine.

We were thinking using chip clips, but you cant use it on inner sections as the material needs some place to go.

Any suggestions on something to buy to temporarily crimp/seal the grain on one side of the pocket?