Sciencey Valentine's Day Gift

What’s a fun new way to reuse an old container? Of course – make a cute keychain!

Safe­ty pre­cau­tions

Warn­ing: only un­der adult su­per­vi­sion.


  • used (clean) poly­styrene con­tain­er;
  • white­board mark­ers;
  • scis­sors;
  • let­ter open­er;
  • cut­ting board;
  • thread;
  • nail pol­ish;
  • oven.

Step-by-step in­struc­tions

Cut the lid off of a poly­styrene con­tain­er and draw your shape of choice on it. Cut your shape out, make two holes in it with a let­ter open­er, and col­or it with white­board mark­ers. Put it in the oven at 180 °C (360 ° F) for ap­prox­i­mate­ly one minute. It should shrink! Now you can put it on a thread and hang it on your keyring – it makes for a cute key­chain! If nec­es­sary, coat your new key­chain with nail pol­ish.

Process de­scrip­tion

As poly­styrene con­tain­ers are pro­duced, the struc­ture of the poly­styrene is changed sig­nif­i­cant­ly. The mol­e­cules of the poly­mer are stretched and ar­ranged ran­dom­ly with­in its struc­ture (such struc­tures are re­ferred to as “amor­phous”), which is what makes it pos­si­ble to form large pieces of plas­tic. Heat­ing poly­styrene re­turns it to its orig­i­nal shape: the elon­gat­ed poly­styrene mol­e­cules be­gin to curl up and as­sume a coil-like form. As a re­sult, the struc­ture of the plas­tic be­comes more or­dered, and its rigid­i­ty in­creas­es.

You can choose won­der­ful sci­ence sets and get them on a month­ly ba­sis for your kids.