There are a few methods to hide the runner marks after cutting but it is not easy. Most modelers sand paper it down and paint the plastic. Me, I cut them with my plastic cutter, a Tamiya's Modeler's Side Cutter, then carefully and slowly, I mean REALLY slowly, cut it it down to the desired level with a penknife (any penknife will do but some claimed that the knives by Tamiya are thinner and better). Always leave a bit of the runner with the side cutter. The remaining bit should be cut down by a knife instrument. Side cutter don't cut as clean as a knife. I usually get a close to perfect cut but there are times where the plastic turns white. When this happens, I scratch them with my fingernails and they do sort of turn back to their original color. This works sometimes but not all thetime. Kinda like magic.

A pic of the bitchy runners
Cutting the runner with a Tamiya side cutter

After the cut

After cutting it down with a penknife
That's all for now. Okuk onak Dayak.