I believe DeviantOllam recommends putting a gun in your bag (from memory a starter gun counts as a gun to TSA but doesn’t have the whole licence restrictions of an actual firearm). Because you have a gun you are allowed to lock it with an actual padlock and the TSA can’t just go through your stuff. If you put a padlock on otherwise they’ll just cut it off and you’re back to square one.

For sewing stretchy fabrics my advice is to purchase an overlocker not a sewing machine, sewing machines will generally suck at stitching stretchy fabrics. If all you have is a sewing machine I recommend triple stitching if your machine has that as a setting.

I’m not a professional at this, I just repair my family’s clothes so if I’m wrong feel free to correct me.