Update v3.5.6:

Here's something useful, customizable drawers!
With this update you can now create your own drawers and fill them with trains & props of any kind, which means quickMods, liveries, official trains, and all props.

You can place them inside these drawers using a sort of "inventory tetris" system following a grid:
(note you can press Q and E to switch direction when placing trains)

As well as trains (liveries, quickMods, etc) these drawers can also store props!
All save data like paint color, material style etc is also saved in these drawers:

Unfortunately you can't store track or "painter" props in these drawers yet, though I plan to add this soon (possibly included in the next update) along with more options for positioning and rotation of items in the drawers.

When you open the new "custom" category in the drawers you can add and remove your own drawers:

The save data for these drawers is stored in plain text (just like a normal Rolling Line save file) in the folder "Modding -> custom drawers"
If you want to copy-paste drawers between friends then you can access and edit these files directly!

I'm working on adding the ability to include custom drawers in workshop saves (so downloading a map would give you access to the drawers the original owner has) and this should be coming in the next update.

Something useful about these custom drawers is that you can use them to store special rare trains like the golden trains and ghost trains:

Along with these new drawers, this update also includes:

Golden trains can now be cloned.
Individual drawers can no longer be picked up (this use to be a setting, but this feature is very out-dated and is no longer needed since drawers are placeable and moveable now).
Fixed bug where the Brazil freight wagons would disappear from drawers after visiting an easter egg scene.
Pressing Delete on PC use to remove props from drawers that should be un-deleteable, this has been fixed.