there are some computer related gadgets out there which, courtesy of the OEM decisions, have to be used with a small battery. E.g. some of the graphics tablet related pens are that way. Perhaps in some situations (like "battery prices just went up by 1000%" situation) it might be nice to be able to mod such gadgets into not using batteries but rather using a power source rated as functionally equivalent to the battery in question. Let's say we would connect this power source gadget via professional "tuning" on the end user gadget, inserting a battery emulating "plug" into the OEM battery holder and supplying power to that plug via a wire going through a hole drilled in the case. What would be the complexities inherent in creating such a power source gadget? Is this something that can be straightforwardly prototyped in a lab and then easily made in an electronics plant? Or are these things not as easy as my naive view of it?