When Sabina was starting to crawl and pull herself up I noticed how often she bumped her head, especially in the cot. I looked around for some cot bumpers and discovered I would get no change from $50 if I bought 2 of them from the store.
So I made her these cot bumpers, with a sweet fabric from Global Fabrics and some foam. Basically they are formed like a long pillowcase with an overlapping joint in the middle, and then ties are sewn in at various points along the side seams.
Now that the twins are sitting/toppling over I have re-employed the cot bumpers in this cot, which we use as a play-pen and spare cot when babies come to visit.
Now that should solve the bumpity bumps of the cot bumpers!