what's happening here? stringing?

[curious aardvark]

to make a mould watertight - you need to print it solid. Now with most slicers 100% infill is NOT solid. usually you need to tick a box in the slicer that adds a solid diaphragm and set it to make one every layer. That will then make a totally solid, utterly watertight print that should work fine for a resin mould. Obviously you still need to get the printing temp and speed right as well. But you can certainly make watertight moulds.

[steveh2112]

thanks, where is the solid option in cura? not seeing it

[curious aardvark]

try prusaslicer instead - cura is the least user frinedly slicer there is. In prusa slicer it's here:

prusaslicer-infill.JPG

I don't give cura disc room on my computers :-)

[steveh2112]

OK, thanks for the tip, why do you prefer prusa?

[curious aardvark]

easier to use, better laid out, not designed for 3mm filament and just a lot easier to find settings.

Cura was okay up to about version 13, then they had a total reboot, started the numbers from 2 and it just became almost impossible to find anything.
too many nested menus.

I actually use simplify3d for 90% of my prints and Flashprint for my replicator clone, Klik-N-Print machine.

Of the free slicers that will run with most machines, prusaslicer just makes the most sense.

There are a couple niggles like the print speed settings being split between a percentage for some settings and a set speed for others.
A percentage for everything is a lot easier and makes mpre sense.

Simplify3d is the best, but you have to buy it.
There was a cracked version floating around a few years ago - but not seen one for a while.

So if I didn't have s3d, I'd probably be using prusaslicer.

kiri:moto is also pretty good, but it's online software and my internet connection is not great, so i avoid online applications wherever possible.

Also the ender 3 is a - deliberately - crippled version of the prusa I3, so it's - sort of - the machine the slicer was developed for and cura is developed for Ultimaker printers, which are quite different in operation.