Create a shape inside a shape in Sketch app

Question

Two weeks ago, I asked if it was possible to fill only one path inside a more complex shape. I found a solution by taking out that one path I want to fill from the inner shape.

I'm now trying to create a shape and fill the inside with the color of my choice. I started with a free arrow shape (svg) and I added two rectangles to create the shape I wanted (see the picture). I made a union between the two shapes and the two rectangles to have a shape in one group.
Problem is, I don't know how to fill the inside of that combined shape...

Is there a tool I can use to have the outline (or maybe, the inline ?) of my combined shape ? So I can have a shape inside my shape and color it.

Answer 1

Getting a simple shape

What you can do is draw a rectangle below, then select both the rectangle and the custom shape and run "Difference". (If this doesn't work well, try Paths > Flatten on the custom shape.) There should be a new combined shape, on which you can run "Paths > Split". In the resulting shapes, there should be one with the inside of the custom shape.

Getting a combined shape

If you don't mind getting a combined shape, it might be simpler to just trace over the shape roughly, move the trace to the bottom, select both the trace and the custom shape and then run "Subtract".

Answer 2

Tin Man gave a nice answer to my problem but I also found a workaround. If you want to fill the color with the same color as the borders you can switch the type of the fill. Non-Zero will fill the entire shape.

On the screen, the left arrow is the one I obtain with the Non-Zero option, the right one is what I obtain with the answer above.