Custom foam inserts have been used by the Aerospace and Military industries for decades. The military employs the use of foam inserts for all tools to reduce FOD Foreign Object Debris. Imagine a mechanic is repairing a million dollar F-22 Raptor engine and forgets one box wrench inside. That $10 wrench just ruined a million dollar engine upon startup.
Engine damage due to FOD. Source: NATO STO
Therefore, the Military takes FOD very seriously and knows the costs of missing tools. The military typically contracts with large companies who have specialized cameras, lightboxes, CNC foam routers etc to make each custom foam insert for the mechanics toolbox. Foam used for tool inserts ranges from 1/4" to 1" thick depending on the toolset. It can either be a crosslinked or non-crosslinked Polyethylene foam with a medium density (2.2lbs up to 4lbs). Polyethylene has proven to be an excellent material for use as tool inserts since it is non-porous, corrosion resistant, and abrasion resistant perfect properties for repeated use in industrial environments.
Easily identify if a tool is missing.
Companies such as TraceMySpace provide custom made foam inserts for any type of tool and just need a photo of your tools to get started.