Spring force for physical push buttons

Are there any design guides or existing studies that provide recommendations for the spring force (e.g. lb/in or kg/mm) of a physical momentary push button that provides comfortable use but also a "well-built" feel (for an adult with normal finger function)?

The buttons I have in mind would be about the size of a finger tip, and directly control quick-release mechanical latching clips (so you'd press, then probably hold for ~1 second while manipulating the device), with about 3.5mm travel. They're printed parts, and I need to find some springs to put behind them but there's a huge range of options.