Inspired by Adam Savage's multitool belt holster, I decided to print something in the same spirit.
This is designed for a Victorinox SwissTool Spirit X, but can be customized for other tools.
Print as plated, without supports.
Can be customized to work with different tools; you will need to measure your tool with calipers, or scan it with a flatbed scanner and count pixels. There is a narrow end (the bottom), a wide end (the top), and a transition area between them you can specify. If your tool is slightly asymmetric, as is the Spirit, use the wider side to determine the transition points. The belt clip can be resized and moved up and down.
Allow for maybe a millimeter of clearance on each side, and more for thickness if you have saggy bridging.