I have started a tradition of making a piñata for everybody at my kids' birthday parties. Normally I enjoy it, but this year I procrastinated too long and needed something really easy. My son wanted a Minecraft theme, so I made creeper piñatas from gift bags.
I started by purchasing gift bags from the dollar store in the size I wanted.
Next I prepared the candy. I went with a Minecraft theme for this too. I found printable labels from various places online and labeled sandwich bags. Here's what I used, but the possibilities are pretty much endless. Also, my nephews laughed at me for getting the gold thing wrong, but I still don't know why.
Torches - Tootsie Rolls
TNT - Pop Rocks
Gold - Twix Bars
Fish - Swedish Fish
Blocks - Mini Starburst
Healing Potion - Wax Bottles
I made sure the bags were completely open (so they made a rectangular shape) and placed the candy into each bag.
Next I sealed the opening with paper mache. I use a paste of half flour, half water, and a little salt (just like the DIY Frozen or Princess Piñatas.)
When they were dry, I covered the entire bag with another layer of paper mache. That was enough for me since I get teased about making the piñatas too hard to crack open, but you can decide how many layers your piñata needs.
I applied a coat of green paint and drew a creeper face with black permanent marker.
One thing I liked about these piñatas was the handle, but they were pretty flimsy. We ended up hanging them by wrapping string around them.
For the favors, I drew a creeper face on green paper bags.
We put the parts for marshmallow shooters inside the bags along with a bag of "ghast poop" to use with the shooters. (They could also be "ghast tears" if your kids don't enjoy potty humor as much as mine do.)