Making a well defined channel, with the appropriate inclination is done with the CNC router. But, even though very accurate, this requires time, a digital 3D model and an expensive CNC router. We found a cheaper and quicker way to get almost the same result. Cutting the channels with a hot wire foam cutter already appeared to be very useful, but it was a problem to construct an equal gradient over the whole channel when the channel is curved. An easy solution is making a cut (or several cuts) in the foam sheet. After cutting the channels at the same depth at every place, put the sheet on blocks with the appropriate height and push it down with a weight. It is flexible enough to follow the proper shape without breaking or bending on the wrong place and the cuts make sure the bending of the sheet follows the channel.