If you can't use the magic wand because it doesn't give the results you need and you then have to manually place the nodes then don't forget the 'Offset' tool.
If it is easier to select the inner or outer corners rather than zoom in and get the node you want then select all of the outer nodes and at some point before your final click activate the offset tool.
Place the last node and then determine the offset of the slab/fill.
Barry.
One of the forum moderators.
Versions 6.5 to 27
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11