So I delete my progress and started from scratch again. This time I will save all my solutions and share them here, not sure why... anyway... my solutions tend to be high in cost and cycles, but use low area. It also seems that I favor pistons and tracks.

Chapter I
1.1 Refined gold - https://giphy.com/gifs/Okh0yKO8SFonN4Vn0i
1.2 Face powder - https://giphy.com/gifs/bFlwNznxkvn21XldWa
1.3 Waterproof sealant - https://giphy.com/gifs/jIw2Zx1Mzy06mPM0fn
1.4 Hangover cure - https://giphy.com/gifs/1NTrZ9hH8hxCgJAeHe
1.5 Airship Fuel - https://giphy.com/gifs/PoJOCRWE39MUr4xyhE
1.6 Precision machine oil - https://giphy.com/gifs/1NZ7Z1xIf973ZmixnS
1.7 Heath tonic - https://giphy.com/gifs/7NM9CMdGtcdidZAGGy
1.8 Stamina potion - https://giphy.com/gifs/5wFapqqjUdWNPiRA1J

Chapter II
2.1 Hair product - https://giphy.com/gifs/KX8fOzAHBuq5Q3ttnG
2.2 Rocket propellant - https://giphy.com/gifs/jIBXZOG6VlD5kbMOnj
2.3 Mist of incapacitation - https://giphy.com/gifs/1kTHXeWLfc3istTeqd
2.4 Explosive phial - https://giphy.com/gifs/Mn4m2FebqmPb1QoNgs
2.5 Armor filament - https://giphy.com/gifs/9xyQXpgumQWgaXkXwf
2.6 Courage Potion - https://giphy.com/gifs/OOSzjeTCr63eMRSMYS
2.7 Surrender flare - https://giphy.com/gifs/RIXrCwD7tApYBpwv0p

Chapter III
3.1 Alcohol separation - https://giphy.com/gifs/QM8AacyiS3I6AvZb1h
3.2 Water purifier - https://giphy.com/gifs/bqbdYPAIq2k9rNndL8
3.3 Seal solvent - https://giphy.com/gifs/csR2blQmtbaYqQvTlH
3.4 Climbing rope fiber - https://giphy.com/gifs/4Nk9xNSFSG7tAHR3Lr
3.5 Warming tonic - https://giphy.com/gifs/XHnsQTmB7cbYf9FdjF
3.6 Life sensing potion - https://giphy.com/gifs/edP1FVjuG3fZFfUfAt
3.7 Very dark thread - https://giphy.com/gifs/1eABwiVJN3yXfkEZHA

Chapter IV
4.1 Litharge separation - https://giphy.com/gifs/ulxyGtx6AeWmxH8V3O
4.2 Stain remover - https://giphy.com/gifs/407RgrQlFZnoGA9vaJ
4.3 Sword alloy - https://giphy.com/gifs/82MkCO5UMJFYIwHcSK
4.4 Invisible ink - https://giphy.com/gifs/myo7dln102ndK9QTIH
4.5 Purified gold - https://giphy.com/gifs/5zvO8Ec8oR80uuzL0S
4.6 Alchemical jewel - https://giphy.com/gifs/lfd5vAtZxnMipLxVGb
4.7 Golden Thread - https://giphy.com/gifs/Bfb7ZcOmCE1wlJeVt3

Chapter V
5.1 Mist of hallucination - https://giphy.com/gifs/3naVZ0LhKML0bhafAD
5.2 Timing crystal - https://giphy.com/gifs/cPXoUVYCeQeHGswNhk
5.3 Voltaic coil - https://giphy.com/gifs/4WEKMAJzC8D3MwCKXB
5.4 Unstable compound - https://giphy.com/gifs/9AIAmd4FewUjTT05Qm
5.5 Curious lipstick - https://giphy.com/gifs/lzuJMwmHgZzwz3auiV
5.6 Universal solvent - https://giphy.com/gifs/1ZDHAXbvQGNfAhErWA

ohhh... impressive. almost 4 times as fast as mine. yeah, it has become a part of my "essential games" list now, the few games I have always installed and keep coming back to

The Litharge Separation was a right bastard because I wanted to design a fast one straight away. Right at the beginning I locked myself into a total loop length of only 6 cycles per object. The reason it's not as fast as that would suggest is that it has a considerable start up time (the time from the first reagent being picked up until its products finish leaving). Once it's running it's processing one input every 6 cycles though, so the longer it is left running for, the more negligible the start up time would be. It's a pity the game measures speed based on only 6 ouputs. :)

Speaking of cycles. I decided to try to see how far I get by only using one arm on a level. All levels should be doable with a piston and a conveyor. Expecting the cycles to go through the roof... This is my chapter 1 (which I did not expect any problems on)

Chapter I
1.1 Refined gold - https://giphy.com/gifs/czZgkT1Yg57pxrylGQ
1.2 Face powder - https://giphy.com/gifs/dn13iHls7wSP7Jrprs
1.3 Waterproof sealant - https://giphy.com/gifs/OPvh6kF0tLjEwYd1ct
1.4 Hangover cure - https://giphy.com/gifs/1USM9bdI3o33LDeHd4
1.5 Airship Fuel - https://giphy.com/gifs/pjwz0dsj25QRYPrGdu
1.6 Precision machine oil - https://giphy.com/gifs/ujvHYxNOZrqLMaXXNI
1.7 Heath tonic - https://giphy.com/gifs/PoCsSpq7zVo7U6kuQU
1.8 Stamina potion - https://giphy.com/gifs/QN47dQ6fXyRqOYn9Or

Chapter II
2.2 Rocket propellant - https://giphy.com/gifs/MVftWyPRE05g6zSm16
2.3 Mist of incapacitation - https://giphy.com/gifs/etU7Tsm39PsJuBLZvh
2.4 Explosive phial - https://giphy.com/gifs/20IpNFknf8OBzBwDLH
2.5 Armor filament - https://giphy.com/gifs/1nP9mVxwYpmOEkj41g
2.6 Courage Potion - https://giphy.com/gifs/2fJMwiTkihi08fbcvI
2.7 Surrender flare - https://giphy.com/gifs/OkhoUvCbLE9j8IMDVF

I'm in the same boat; do it fast or go home. There are a couple I decided to do according to another metric, but for the most part I'm committed to doing it as fast as possible (or at least reasonably close). Universal Solvent is my current puzzle, and it's really annoying me because I'm uncompromising with regards to speed. There are 12 elemental outputs, and 4 elemental inputs, so truly efficient design should pick up each input 3 times (so it should theoretically be doable in a 6 cycle repetition) but since I'm limited to one wheel the physical constraints of moving around all those pieces has proven problematic.

For 'story' reasons, I tried to switch my focus in Chapter III to cheapness rather than speed, but after a few puzzles I reverted. Speed is just so much more satisfying.

I did a couple by cost... it takes so fricken long to run the instructions.

Life Sensing Potion... in 558 cycles. Or worse, Unstable Compound in 735 cycles. Ouch!

Curious Lipstick in 153 cycles was a breath of fresh air by comaprison. (also, I'm aware the dual-arm apparatus on the left could be smplified. The original reason I did that isn't relevant to the final design, but I wasn't going to bother changing it when the design very clearly isn't winning any awards for cost anyways)

Well, after much frustration and many dead ends, I finally got the Universal Solvent with a satisfactory amount of speed - 90 cycles. The design is a complete and total monster, and is well worthy of the final story mission.

Chapter IV:

Litharge Separation: https://drive.google.com/file/d/1_u5k05Ql3-V0YvYfIiBLOwiMc5NLNVMw/
Stain Remover: https://drive.google.com/open?id=1yVDkfW3gpBWAJXKDhIb1bSUN5ULXxs_P
Sword alloy: https://drive.google.com/open?id=1RR8qpqmNtcY0gdCVy1SaIbvHsgRUbUco
Invisible ink: https://drive.google.com/open?id=1nKm36yu2i0miafo685lb0L893rYKoRZN
Purified gold: https://drive.google.com/open?id=131SjcWAXA1LOA0T8Ikrofh-Tz4PCFwDv
Alchemical jewel: https://drive.google.com/open?id=1TZ8iULV_Ec-IKnVqmJIDdIwBujbb88L3
Golden Thread: https://drive.google.com/open?id=1gPePYySPQ8DkOYur9xPlksK5Fyz9L9Dv

Always interesting to compare solutions. I'd forgotten about this thread, but I've still got my solutions to compare.

Lithurge Separation our solutions are very different, and yet we ended up with exactly the same number of cycles.
Stain Remover
Sword Alloy (it looks like the game bugged out and only shows the last few cycles there rather than the full process. I had a little arm that activated at the very end to move the whole thing forward when it was just big enough to give me victory, shaving off some cycles. You can still see roughly how it worked, though)
Invisible Ink I love how this scenario lends itself to symmetry.
Purified Gold I think everyone's "fast" purified gold implementation ends up looking mostly the same, so here's my "cheap" implementation. It took me several days of slowly working at this one before I finally got it working without any bugs. When it came time to finally run it for real and produce 6 units of gold, I just walked away an came back ten minutes later ;-)
Alchemical Jewel my original solution went for a more radial approach like you did, but for my second pass I went for a "sandwich" approach. This allows me to avoid collisions and start building the next alchemical jewel while the first one is still assembling, resulting in a significant improvement in overall time.

So I got stuck on Universal Solvent over a year ago and didn't pick up the game in that whole time. Until this evening that is.

I think I was aiming a bit too high in terms of speed. Once I just cracked on and made something that did the required thing I found that I'd done ok on the speed histogram anyway. Then I remembered I'd put a wait command in an arbitrary place further down the timeline, just to make it a bit easier to work on. Anyway, when I took that out the speed virtually doubled and I'm on the fastest column of the histogram so I'm dead proud.

https://drive.google.com/open?id=1_1Obpkp9D63MWh6I1V084_zUsc03-2mf

Ooh, yours is cheaper and smaller while having the same speed!

I'm a very messy designer, I don't tend to pay attention to space at all. I'd love to see yours! It seems to have been deleted from the host though.

You want an 'alternative' solution? Never came back to this one, so still as messy as before

https://gifyu.com/image/lPLi

Nice and space efficient compared to mine. I did go and shrink mine a bit before recording the gif, because it was too zoomed out to see anything!

Ok, I'm pretty proud of this. My first attempt at Silver Paint.

GIF: https://drive.google.com/open?id=1QuTYpir4KcL8r83qdeJdIvdSA_03y7K5

Histograms: https://drive.google.com/open?id=1AWQLsLgHHt_4UOdMHZoo3OiexB9Zp2VY

I was still aiming for speed, but I had such trouble working in the confined space that I expected it would be really slow.