While I was pregnant with the twins I saw some sellers on etsy selling cute monthly stickers for onesies. I liked the idea but didn't want to use stickers - I wanted something that would last longer and could hold up in the wash (I really wanted something they could maybe keep for their kiddos). But it also needed to be easy enough for me to make two of every month. Enter freezer paper.
Freezer paper is awesome. I use it to trace patterns (so that I don't cut up originals), and they store easily. Freezer paper also makes great stencils - you can trace any design onto it (I've heard you can put it through a printer, but mine doesn't like it), and cut it out and iron it onto fabric - the shiny side will stick to the fabric. Then add some fabric paint and voila!
Since hubby teaches math we decided not to use numerals for each month.
For their three month shirts we used iron on transfers, since it would have been a lot to do with a stencil. They don't look as nice quality-wise, but they are cute nonetheless.
This has been a really fun project, and I am looking forward to more freezer paper projects!