Today I made one for his little sister who is almost two and I thought I would share the idea because it is so quick and easy and cosy and comfy and practical...perfect!
Bring the short sides together and sew in the longest zip you can find leaving a small opening at the top. Sew a seam the rest of the way down to the bottom.
Sew across the bottom and the top, leaving a hole with plenty of head room.
I cut armholes and blanket stitched the edges for my boy's so he could sleep in it at night and put his arms out to undo the zip in the morning. But he never uses the armholes, he puts his arms out from the top, so I didn't bother putting holes in my little girl's. I still may at a later date if she needs or wants them.
I finished them off with iron-on motifs.
After all the rough play my boy gave his sleeping bag, when it started coming apart at the top and bottom I used crochet cotton to blanket stitch over the machine stitching. Now it should last awhile longer, until he grows out of it at least. Then I'm thinking I may open the bottom and sew some extra length in a contrasting colour, if he can't bear to part with it!
PS And here's another I made for my niece's birthday present. As she will be 8 I sewed the long ends together and inserted a zip to give extra length. It's a little narrower but it is still snug and cosy!! I want to make one for myself now!