Hey man, great job on the mod. Using it for pYanodon's myself :)

I had 2 suggestions that came to my mind...

The first, configurable research cost in the mod settings. 1000 logi science isnt much in vanilla, but in some modpacks it's way too expensive. I went and personally modified my costs in the game file but most people wouldn't know how to.
This should be relatively easy to implement, the factorio modding API wiki explains how to create settings.

The second, configurable width/size. 6x3 is very reasonable, but for instance I found myself wanting 6x1. And even 2x1.
Some modpacks have smaller/larger train wagons so a configurable size would make sense. Or at least a few more options than just the one set size.
Idk how much effort this would be as it might mean needing to do some magic with assets so the containers don't look wrong.

Hey, thanks I'm glad you're enjoying it!

I can definetely add some config settings for the cost and inventory space, that is no problem at all.

As for the physical size, that is a big task to create new sprites, which is not something I'm looking to do as I'm not that good at it and so it takes a while to make it look great. In this case I'd rather point you to some already existing options for other sizes you may like. I chose 6x3 on purpose to balance out the big container vs multiple small ones, so you get the advantage of not requiring as much belt space for balancing, but the container itself takes up more space. This is a use case I personally was looking for to give trains that little bit of a boost to make it more competitive with stacked belts these days, without making it completely overpowered.

Anyway, there's another mod that adds in 2x1 size containers (https://mods.factorio.com/mod/wide-steel-chests)
For 6x1 you could look into using Merging chests (https://mods.factorio.com/mod/WideChests) which I believe also have addons that lets you merge arbitrary dimensions together to fit what you need!
And ofcourse, there's AAI containers (https://mods.factorio.com/mod/aai-containers) for more sizes as well.