1a. A pattern for a cardboard box close to 50cm cubed, or perhaps a cylinder 50cm diameter by 50cm tall? Get one that has interlocking tops, bottoms and sides. Make sure you have big tabs that will self-lock, like the tops of a normal cereal box. The pattern, cutting and assembly of this box is important.

1a. You’re gonna need some wings or parachute that will also interlock into this box. This might be one piece that slides through cut slots. The interface between the box and wing/parachute is critical.

2. A similar box approximately 25cm cubed. No wings here.

3. A good paper shredder. Most poster board is in layers, so you’ll likely de-layer the board before you ruin your parent’s shredder. Think thin. Get those layers as thin as possible, perhaps soaking in water, then drying in the over or microwave. Make the boxes, then shred whatever is left over.

Obviously, the shredded paper goes inside both boxes to cushion the fall.

Other things:

a) Be creative with soaking in water. Sure, you can’t add anything but you can add the water, then dry it out, thus keeping the mass of the paperboard the same before and after it’s soaked.

b) you MIGHT get lucky and while you de-layer, you can experiment with the glue that holds it together. Perhaps acetone will help? I doubt it, but it’s worth experimenting, as glue is your friend.

c) Rule #1: the outer box CANNOT open. If it splits apart on impact, it’s over.

d) Be critical and careful of your folds. Use a sturdy straight edge and an Exacto knife. Precision cutting is vital.

e) Experiment, test, experiment, test, experiment, test, experiment, test, experiment, test, experiment, test as many times as you can afford.

but

I think if you bend the posterboard in the middle from all sides creating a sort of hill the egg should safely slide off the board once it hits it

But you do have to have good aim