I forgot to order the correct bearings and instead of waiting 3 weeks for them to arrive from Ali i decided to use some of the spare POM wheels i had and remove the bearings.
The bearings can be removed by inserting a small screwdriver and pushing on the opposite bearing through the hole. (you cant push both bearings since there is a lip holding them in place)
The author remixed this model.
outer diameter changed to Ø16mm and a depth of about 5mm