Most important, all lithium polymer batteries have reasonable tolerances(±0.3mm — ±1.0mm） It is hard to achieve a battery without tolerance based on model battery development technology.
If your mechanical constraints is required require (without dimensions tolerance). Then negative tolerance is one of the best choices to fulfill your custom requests.
The capacity depends on your dimensions.
The larger the dimensions,the capacity will more larger.
How to custom a battery?
1. please let us know what's your applications, the continues working current and peak working current.
2. please let us know what's the max size of the battery you can accept and your expecting battery capacity.
3. do you need protection circuit board with the battery ?
4. what's the length of the lead wires.
5. Connector name and the connector direction. (which pin connect to the positive.)