I printed in black PLA and used this with the Havsris cord set:
https://www.ikea.com/us/en/p/havsris-cord-set-with-switch-black-60490053/#content
The cut-away is so it sits flush against the wall when hung on the wall by the cord. In my case, the bulb is hung from above a few inches from the wall so it illuminates the wall evenly.
Should also work with STRÅLA and other similar Ikea products.
The author marked this model as their own original creation.