Here is a little DIY how to on skimmer mod'ing. It's super easy to do, doesn't cost much and always makes huge improvements to skimmer performance. I've done at least three different types now, each a little different.
Here are some examples on what to use and how to do it.
Basic scissors or angle cutters, mesh, and spare impeller. Don't use your only one incase you break something like the ceramic shaft.
This particular impeller for a Euro Reef Aqua 55 Classic has a needle wheel design. There are post coming out from the center in a fan pattern. They are also staggered with one high one lower and then more needles coming off perpandicular to the axis needle or post. I simple cut away the lower row.
I then cut really thin strips of mesh to weave in between the remaining posts, up and down.
There is no real right or wrong here. Just do it, experiment and try.