This orange piece in this two pictures is from is from one of them Christmas sets that nearly everyone gets.
the one below I think might have been an Easter egg.
So to start we need some form of packaging & expanding foam that you'll get in any hardwere.
Next put the foam into packaging only fill it about one third of the way, rememder this is exspanding foam.
You'll next need to cut the foam off level with the bottom of the packaging.
After that you can add more detail if you like.