Can I use a plastic bag?

Model glue is appropriate as it is designed to melt the plastic and "weld" the parts together. Super glue is much easier to take apart whereas model glue will not...

No. You cannot substitute a microwaveable plastic bag with a regular plastic bag.

Depending on what type of plastic it is, it probably will stick to it. You can put parchment paper sheets between the mold to avoid this, but the heat from...

You can use a bag or a bottle, but it will work best if you use a film canister (with holes poked in it) or a salt/pepper shaker, because it...

No, the table cloth is not strong enough and will rip. Also, it is likely not long enough.

No, as it is not made of a reflective signal material such as aluminum is.

Most offer an easy push-to-eject function that, if pushed just right, will allow the foot to come out without breaking. Give it a little more force, and with the end...

Try using a pair of pliers on the plastic and a screw driver on the screw. Turn screw counterclockwise to remove. Repeat for each screw.

It shouldn't be a problem. Usually D string magnets are raised higher than the others.