I wanted to convert these IKEA stools to bedside tables. The reason was that they match the rest of the bedroom furniture abd there was limited space near the beds, so we could not really use normal bedside tables.
To add a shelf to it, I just got an extra shelf of KOMOLEMENT and cut two pieces at the right size, using my table saw.
I decided to remove the diagonal support pieces, to make it look more like a bedside table and less like a stool.
it was then easy to fit the custom shelf using a couple of plastic fittings:
I used iron-on tape I bought on Ebay to hide the cut sides of the shelf. I got 5cm, to cover both the shelf side and the horizontal support piece. The tape was a but wider than required, so I removed the excess using a chisel. It was the first time I used this simple iton-on tape and I think it worked pretty well.
And here is the final result. One extra shelf where we need it!