Magnet cockroach is mischievous and bad taste.
I recommend a butterfly. It's rather easy.
The wings are cloth printed by iron transfer paper.
You can choose any butterfly from web or books.
The body is made of felt and fiberfill.
Bind the neck and attach button eyes.
Its antennas are embroidery threads hardened with some glue.
As a butterfly's body is thin, small magnet is good.
If the magnet is bigger, attach it outside.