I am not very crafty, but thanks to the internet that doesn't really matter! I found a fun craft, the stained glass heart craft on this website and altered it a bit, cause that's what you have to do when doing a craft with 2.5-3 year olds! Also, as are most crafts with 2.5-3 year olds you will end up doing about 90-95% of the work, depending of course, on the "I can do it-ness" of your child.
Find an eager toddler and a table. Protect your surface with newspaper or towels you don't mind staining with crayon wax. Find crayons, pencil sharpener and wax paper.
Recruit your toddler to make crayon shavings.
Recruit your toddler to fold over the piece of wax paper.
YOU take the iron, on it's coolest setting and slowly iron (I chose to iron on top of a piece of cloth so I wouldn't get the iron waxy) checking every couple seconds at the melting progress. It will go REALLY fast, so seriously, check like every 2 seconds.
Cut a heart out of a harder material that you can trace.
Trace hearts onto the wax paper. Any size, any shape.
Recruit your toddlers to TRY to cut out the hearts.
Toddler scissors didn't cut the wax paper very well, so I ended up doing this as well.
We chose to make a heart chain with all our family members. But you can do whatever you want to with the finished hearts.