Model Rocket Builders Marking Guide

Easy to use and accurate. Simplifies measuring and marking tubes for proper alignment and placement of lugs, fins, tube-to tube configurations, etc. Way easier than trying to wrap paper around a tube to mark it for fin placement, or to use the door-jam method for straight lines. The pencil marking guide to mark around the circumference of the tube is great for setting up a cut line, or other accessory placement.

This is extremely helpful in building. If you want a more sure way than your door frame, this is it.

This works fine, especially for smaller tube sizes. For larger and longer tubes I prefer to a piece of aluminum angle from Home Depot.