upload 2 part model as two separate files or one file with two parts to JLC3D?

[dentaku]

I have an enclosure that's about 104mm by 72mm. It has a top with curves, bosses, cutouts etc. and the base is a simple rounded rectangle with 4 chamfered holes.
Is uploading the top and bottom separately the proper way to do this if I want to RESIN print it at JLC3DP?

It looks like they charge by volume of resin used so if there was a way to send them a file with both the top and bottom together I'm assuming it would still cost the same but make it more difficult for them to deal with.

I know this might be a dumb question but I've never sent anything out to be 3D printed before.

[dentaku]

I uploaded a file with both the top and bottom in one .3mf file and it just ends up being the same price as doing two separate files because obviously it's the same volume of material.
The 3D preview on the site also says "number of entities: 2" so I guess it would still work that way but like I said, I'm just making it more complicated for them.