Printing Hollowed models w/ PLA?

Hello,

I'm fairly new to 3D printing in general but am an experienced 3D Artist. I got myself an Ender 3 printer w/ PLA filament and have been experimenting with different prints but after watching some videos i noticed people were hollowing their models for resin prints. Though this has me wondering if this is even necessary for PLA filaments that you plan to resin cast later? Bringing the model into a slicer like Cura has a shell/wall thickness option already so is it even necessary to hollow out the model in a 3d modeling software?

It's rarely necessary to hollow an FFF print, especially if you're going to perform casting as part of the project. You use the infill to provide for appropriate support of the overall model as well as to provide for a smooth upper layer surface.

If you're going to use a model as a coin bank, you'd want a hollow inside, but you'd also have to ensure the design provided support for the skin while it was printing.

One can save on filament by using lower infill percentages. Resin is many times more expensive than filament, hence the desire to have hollow models in that process. Another practical reason is if one prints a non-hollow model on a resin printer and the inside is uncured resin, later mechanical failures with the model will result in leaking resin. It's considered a hazardous substance, and you don't want the risk. Filament is pretty low risk in comparison.

The cura wall thickness value is valid but provides for skin strength and the system designs the infill from that reference point.