Here is a list of recipes I suggest should be changed to make casting more worthwhile than just using an assembling machine.
1 aluminum plate -> 2+ aluminum plates:
Bracket,
Fluid chamber,
Roller chain

1 copper plate -> 2+ copper plates:
copper pipe/copper pipe to ground,
copper cable

1 iron plate -> 2+ iron plates:
iron pipe/iron pipe to ground
girder,
trigger

1 titanium plate -> 2+ titanium plates:
spring

1 steel plate -> 2+ steel plates:
Rivet,
steel pipe/steel pipe to ground

Thanks for the suggestion, these were added more as a proof of concept, i will have to look at the actual balancing at a later date.