Sammi I have done 4 competitions now. You can use cake or dummies for your pieces. I have used both it totally depends on what I am trying to do. My wizard of oz and Charlie Brown pieces both had delicate pieces to insert so I used cake for these entires since I felt it would give me less resistance. My last show I started the cake 4 months in advance. Most shows have the rule of the entry can’t be more than a year old.
I am totally addicted to competitions now. I say everyone needs to try them at least once. Hope this helps.
