That is, if the splicing angles can add up to 180, seamless splicing can be achieved.

For example, if each corner of a regular hexagon is 120 and there are three corners 360, then three regular hexagons can be seamlessly inlaid.

Or two regular hexagons and two regular triangles can be used.

Because the sum of the internal angles of any quadrangle is 360, four identical quadrangles can be seamlessly inlaid by overlapping their vertices.