OpenSCAD drill guide

I don't know how to drill perfect holes so I was searching for a good drill guide. The simple metal drill guides of aliexpress and similar looked ok, but there needs to be a solution with 3D print. I found this cool drill guide https://makerworld.com/de/models/1022957-vertical-drill-guide by @pomguy.This seems to be a 3d print copy of the metal versions. I liked that they are compatible with the exchangable metal guides. What I do not like about it, is it's size - some of my drills are not long enough to drill deep while using the guide. So I started to duplicate it in OpenSCAD and did some changes. Biggest change is, that it's shorter. I don't need the tube guide - or if I happen to need it, I print another guide. So I took that out. I also reduced the strength of some parts, as I don't think that is needed. I kept the compatibility with the metal bits and so my guide should be compatible with the bits by @pomguy.My Version doesn't need supports. In the files y