1 piece of wood (found in Dad's wood pile)
Paint (from a previous project)
Metal rim tags (enough for all the b-days)
Picture Frame Hanging hardware
Alphabet stickers (optional)
The piece of wood that I reclaimed was already the perfect length so no cutting was required. I just needed to do a tiny bit of sanding before I painted. The only part of the wood that did not get painted was the back. I didn't think it was necessary. Once the paint dried I drilled twelve holes for the hooks. I wanted everything to hang flat so I drilled the holes for my hooks on the bottom. Note: Read the directions for the type of hooks you purchase to know what drill bit to use. Once the holes were drilled I screwed in the hooks, one for each month. I tried to keep cost down so I opted to make my own stencil using my computer and a fun font and then painting the lettering on. You can also purchase the lettering or phrase you want at any craft store if you want to speed things up. I used alphabet stickers that I already had for the months to give the piece a little pop. After that just secure your picture frame hanging hardware and you are ready to compile your birthdays.
I lucked out and found my metal rim tags on clearance at Staples and they matched my yellow paint too so that was a double bonus. I wrote out my names and birthdays and then used a small hole punch at the bottom of each tag. This second hole allows you to secure the next tag underneath. Securing my tags onto the board was really just trial and error. The first try they were to long and too far apart. Second go around I cut all the strings to two inches. The first birthday of each month is tied to the hook and then each tag after is tied to the previous one. This did take a little time but I am pleased with the finished product.
Hope this gives you an idea on where to start with your Birthday Calendar!