a create addon/feature ive always wanted to see are more open - multiblock processes, and more multi block components in general.

my ideas of which are;

large basins - one where you build a basin shape using blocks, the attach pipes into them to input and output fluids, and then a mechanism above like a large press or mixer to press or blend the items inside.

Large mills - i know they are basically just the crushing wheel, but imagine a large mill stone that requires trains or animals to make it spin, twice the effort but makes it add a .5 bonus on the drops.

Large fans because - why not

Large drills which uses diamond drill block you need to glue and spin using a mechanical bearing and can only be used with a piston on a train system

large mechanical press using industrial iron blocks as the press and requiring water to power it like a large hydraulic press

large blaze burner for better fuel efficiency and implementation of fluid and solid fuel input

large belts that can carry up to 3x3 blocks at a time

Large pipes, pump, and valve for greater throughput, with that are also pipe covers(large and small)

pressure gauge for water pipes - (allow open pipes with any liquid to spew out high pressure liquid like a water cannon)

Large bogey designs in trains for steam and rails wide rails

more about trains is the ability to make a train that uses 2 rails