I have made gibs for a few machines, but not for the Unimats. However, there is nothing too critical about them. Start with a bit of brass strip the same thickness as the old strip, or the thickest you can get that will slide into the gap left when you took the old one out. As you can see on the picture you posted, you need to bevel the edges at 60¡ã to match the dovetail. This is just a filing job, done by eye. The exact dimensions are not critical, provided the strip is an easy fit in the space with all the screws undone. Then just slide it in and do the end screws up until it feels right. The middle screw should be used to lock up the slide when you need to, not for setting the normal feel of the slide. If the strip tends to slide out in use, you can drill or file a recess for one of the screw points, or just file the screws to a sharper point - that will dig in and stop the strip getting away.
