TIP: Using the F2 Add-on
Why Blender Stack Exchange recommends it
Blender Stack Exchange answerers link it when someone needs to fill gaps or create faces quickly and F2 is the suggested tool, even though the video is old.
Recommended by 3 people across 3 different months, 2016 to 2024.
What it is
A short 2013 CG Cookie tip video demonstrating the F2 add-on for Blender, which speeds up polygon modeling by making faces quickly from selected vertices and edges. It was recorded in an older Blender version, so the interface looks different now.
What people said
Recommends lemon · 2016-05 · Blender Stack Exchange · on “How do I fill an area with vertices lined up in a grid over a complex surface?”
Bridge egde loops and/or F2 addon can do the job here. But i dont think any tool can automatically do it all in "one click" for you here. Bridge edge loops : select two opposite edges parts (with same accound of vertices in each) then ctrl+E and validate "bridge edge loops" : [LINK] F2 is an addon to easily make faces (mesh_f2.py). A tutorial and download link here : [this video] [LINK]
Recommends Jason Mohamed · 2021-09 · Blender Stack Exchange · on “whats the most efficient way to close close gaps?”
Greetings George and welcome! There are a couple of different methods that come to mind to fill the gap you have pictured there. Hit F on the keyboard with both edges you have selected there and it "fill" the gap. Take note this will leave you with an extra edge you will probably want to dissolve so that all four edges are properly connected. Delete the face and with the open space and select any one of the surrounding edges and hit the F key which will create a face that will fill the void and should be connected properly to all 4 of the surrounding edges. In Vertex mode try the M key which will merge by distance. You may need to adjust the merge distance and will want to pay attention to w
Recommends John Eason · 2024-07 · Blender Stack Exchange · on “Fill a face with only 2 sides known”
Try using Blender's built-in F2 addon. That should do exactly what you want. There's a very old (11 year-old!) but still relevant tutorial from Kent Trammell at CG Cookie here [this video] which should do exactly what you want.