TLDR I have finished my latest factorio megagigabase. I left it running over the last two hours (in game time) and it has averaged 15.7 RPM.

Here is the album of the main base

Here is the album of the bootstrap base

Here is an extra album showing some more detail about how selected things work

I decided months ago that I wanted to build a huge base, my original plan was to aim for 10 RPM but after /u/accidentalchef's 10 RPM base I decided to go bigger. So my aim was for 15RPM.

I wanted to keep to vanilla entities. But I allowed myself some mods.

The base only NEEDs:

• Railtanker - I liked the idea of this one and I wanted to split up the oil processing chain. I am counting rail tankers as vanilla as they are about to be added to the base game.

However, I couldn't face not having:

• UPS-up - need every drop of usp I could get
• Score extended - a no brainer really. Unless you manually want to click launch every 4 seconds. (although the game only runs at 15 ups so that's 16 seconds in real time)

I also used a number of mods to help out:

• long reach
• squeek thru
• Crafted artefacts - the base uses ~ 200K level3 modules. I managed to harvest ~30K before I gave in and installed this mod.
• FARL - I used this to lay the solar fields. Even with 20,000 bots, 2 million solar panels is going to take a long time!
• PersonalTeleporter - getting around the base was taking forever particularly once the UPS really started to drop.
• TrashLandfill - at one point after de-constructing a load of stuff I had huge amounts of intermediates that I couldn't use, this seemed like a nice way to get rid of them.
• Radarplus for RSO - I wanted to have full real-time radar coverage of the entire base so I could see when trains got jammed, this helped out with that.
• blueprint string - to import blueprints from my prototype base.
• Filtered deconstruction planner - when I need to deconstruct things, this was really useful to be able to remove everything but roboports and power poles.

I used console commands & creative mode to spawn in the resources and to move around some water. For me the interest was in building a base that could do all the processing. The resource gathering part at these scales would be incredibly boring. I also used a console command to make me run faster to counter the effect of the lag. If I had known about it I would have used the coffee mod. I set it to always day, so my solar panels were more effective and I didn't need accus. As you can see the solar field is still huge! I preferred doing this to using an advanced solar panel mod. Biters are on peaceful and more or less completely removed from the map.

However, every entity on the map was made by a machine (or by hand) and placed by hand or by a construction bot, except the solar field that was mostly made with FARL.

Some stats about the base:

• Hours played on this map: 467 (although over half of that was previous megabases)
• Rockets launched: 14865
• Copper cable produced 1.5 billion
• Green circuits produced 576 million
• Solar panels produced 3.7 million
• Concrete required if I wanted to concrete the entire base 33 million. (so I went for the natural look)
• Construction bots: 22118
• Logistic bots: 20048 (although only 63 are doing anything at time of writing)
• Trains: 283 each with 6 locos and 12 cargo wagon / rail tankers.
  
• UPS: ~15 Nearly 4 RPM in real-time.

Design Philosophy

I didn't want to just design an efficient 1RPM base and make 15 copies of it. Neither did I want to have any of the production split into multiple sub-factories.

• I wanted a single place where all the steel was made and another where all the copper plates were produced etc.
• I didn't want to worry about micromanaging multiple train stops for a single resource. This produced some design challenges particularly for green circuits (highest throughput) and steel (most machines required)
• This will all be much easier when 0.15 hits and we can close a station from the circuit network.
• I also wanted an expandable design.
• I chose to use single direction trains, 6-12 (although 3 of the locos are on the back in case I ever changed my mind!) These trains were big enough to be efficient but not so big to be unmanageable.
• This meant I had to use loops everywhere but it worked in the end.
• I decided to have the different sections of the base joined by a pair of main lines one going left to right and one going right to left. Effectively making the entire base a big loop.
• Some of the tracks joining the main line only connect to certain tracks to separate different resources.

Edit: forgot to mention that I used FARL to place solar field.