[Q]: Objective: To make your free standing bookshelf more stable.
[A]: Attach a premeasured sheet of plywood to the back of the bookshelf using a hammer and nails.

[Q]: Objective: How does a dial test indicator work?
[A]: A test indicator measures the deflection of the arm, the probe does not retract but swings in an arc around its hinge point.

[Q]: Objective: To make a lamp using plastic soda bottles safely.
[A]: Use LED lights on the inside.

[Q]: Objective: open a stuck jar
[A]:
Go a step further and use the tip of a butter knife, a bottle opener or even a flat-head screw driver as a prying device. Insert the tip of the chosen object under the rim of the jar lid and lever it out. Move around the rim, inserting the tip and applying leverage, until you hear a small pop. The popping sound is the seal being broken. Once this has happened you should be able to twist the lid open with ease!