The current Keykos factory takes two space banks and a meter. There is a long standing proposal to deliver a resource packet in the place of these. The packet would be delivered in the form of a fetch key to a node with these and other resource keys in conventional slots. In common cases this packet can be passed from contractor to sub contractor unmodified. Any user of the packet is alternatively able to create a modified packet with one or more of the resource keys replaced by a probably weaker, and probably subsidiary key.
The packet eases a problem where a trusted complex of domains are deleted by recalling their space via their bank. If the meter were turned off before the bank was invoked, there would be no execution during the time where peculiar subsets of the space had been recalled. Correctness proofs seldom consider these states.
I suggest this pattern here for mufflers as resource. One of the packet resources is an input muffler stream that the factory yield will recognize as a means of recording units of work and demanding payment.