Fill hollow model

Hi,

New here and to 3d printing, bought it earlier this year and have been using it to print off test pieces of my cad drawings before having them machined.

I was recently asked to print a couple of figure models which I didnt think I would ever use the printer for but accepted out of curiosity and thought it would be handy to learn.

One stl file i purchased was fine for the job but the second I would like to modify.

I got the baby yoda with heart stl and have scaled it down to 60% but I would like to make it not hollow, at this smaller size it is a bit fragile and id like to make it solid to increase the strength but all i seem to be able to do is make the walls solid. I filled one with resin to get around this but it didnt fill the head and when i dropped the model the head split.

Is there anyway I can make the centre of this solid?

TIA

increase the number of the walls until it fills the model.

You can usually fiddle around with infill enough to make anything solid.

You can also load the stl into meshmixer and make it solid.

Likewise windows builder is actually useful for that kind of thing.
And as a 30 year computer professional, I can count on one hand the number of times I've ever recommended a microsoft program. But builder has it's uses.
It's particularly good at adding text to an existing model. Even flows it round corners.