I found that the brake reservoir lid on my motorbike was stuck fast. Of course you can buy a £25 tool to deal with this, but instead, I improvised a small device using the Eitech construction system. Two sliding elements with prongs are placed on an axle. One is fixed and the other moves without rotation.
This allows for a controllable pinch pressure to be exerted on the reservoir, with one hand, whilst also twisting the top.
