First you need to print the monster.You can download the file from Thingiverse
https://www.thingiverse.com/thing:3812070 for free and start printing!
Step 1: Clean Every Print Mistake
You can use an sharp knife and sandpaper to make everything clean.
Step 2: Style Up Your Monster!
Here for I used spray paint to get it done very fast.After drying I used acrylic colors for the mouth.
Step 3: Done!
Put everything in.