This isn't the prettiest model, but it is functional enough to solve my issue. I didn't like that the Fiskars thread snips I use for sewing lay in an always open state, apparently newer models now have a closure mechanism. I designed this cover to keep the blades closed for storage and safety, and to avoid blade damage.

The tab to keep the cover in place only works from one side of the tool, due to the design of the handle.

Included is the fusion file if anyone wants to make a nicer looking solution.