homemade 10 second sling
All you have to do is take a long-ish tshirt that is about one size too small for you. (maybe even 2 sizes too small if it stretches a lot.) Lay it out flat and cut across from under arm to under arm, leaving you with a tshirt tube. Slip over your shoulder and insert child. It really works! (I could not get a good picture to save my life so Ruby was pretty crabby by the time I got this last one.)
Depending on the weight of your child and the length and stretch of the tshirt your little one may need some extra support under the bum. I think one of these would be great to keep in the car at all times and it would be so easy to make a solid black one (or some other manly color) for dad. fun!