Any funnel, in addition to its direct purpose, can be given additional functions, for example, dosing for pour liquid.
This will require a small improvement in funnels, available to everyone. At the top of the socket, a jumper (plastic or metal) with a hole for the rod passing into the tube of the funnel. Bottom stem is attached to the tube, and the top head with a suitable spring.
The spring lifts the rod and plug covers the hole. Click on the head — tube will flow as much fluid as required. On the inner or outer surface of the socket, it is possible to put graduations for accurate Otmar liquid.