This is a parametric launch guide. By changing the rail setting between true or false, it will output either a 1010 rail guide or a launch rod guide. The rail_* values could be modified to fit other sized rails, otherwise they are the correct dimensions to fit 1010 rail currently. The rod_* settings change the size of the rod you're using, and then there's basic settings for the guide's length and the rocket diameter.

Epoxy doesn't always adhere well to 3D printed plastics, so use appropriate adhesives and ensure that you have a good bond before launching. I've used this model on D motor sized rockets up through level 1 high power models with no issues.