There are many great ideas on Pinterest and blogs about making Advent or December Count-Down Calendars. I attempted to make my first and it turned out OK for our 3-year-old grandson. It is not as elaborate and complex as some, but worked for us this year.
I bought small sacks at Walmart for 25 cents each. I printed the numbers on card stock and glued them on. I bought little party favors again at Walmart and divided them up among the sacks. The clothespins I sprayed silver with some leftover spray paint. Our daughter provided the cord and put the whole thing together under their kitchen bar. Grandson H. was happy to open the first few (didn't get mailed off to them very early so they just received it Dec. 3) and gave me a big "thank you" on the phone last night!
For a toddler I think they are just right. I will do the more elaborate ones with activity cards, or such, in the future when he is older. Meantime, we all are happy with this one!