Question about varying fill density

[graybearstx 0]

I have a part that is basically a well so it is printed with the full surface in contact with the table

and the sides printed up.

However there are places on that face that need to be 100% fill. Can I specify subareas to be printed

with 100% fill while leaving the rest of the fill at 20%? I'm using Cura latest download.

[gr5 898]

There's sort of a plug in that does this but it's ugly - you slice it both ways and the plugin combines the 2 gcode files together I think. Much better to use simplify 3d (S3D) which costs I think $80. It seems to work well for most people but has a higher learning curve I think.

You can also increase strength in CAD by putting in micro cavities where cura thinks it's seeing walls and prints more material there.

But PLA is pretty incredibly strong even completely hollow. Could you show a drawing of what you mean?