A living willow Wigwam is one of the simplest structures to make. Work out how wide you want the base of the wigwam to be and ‘draw’ a circle on the ground. Calculate how many of the longest whips you want - work on one every 18 inches / 2 ft - leaving an opening for the entrance and then push them into the ground (about 6 to 9 inches is sufficient for them to root - go deeper if you wish).
Tie them together towards the top.

Use slightly shorter whips to add 2 diagonals per gap - except at the entrance - planted diagonally to encourage denser side growth.

Ideally weave the diagonal whips ‘in front of one vertical and behind the next’ as this makes the structure more rigid -  although tying the whips together may help while you are working, especially towards the tips.

Where the diagonals go across the entrance simply bend them around the vertical whip a weave them back into the criss-cross pattern.

This is the same living willow wigwam a couple of years later in full summer growth. The new growth can be woven into the structure, cut off as it grows, or left for a shaggier wilder appearance, if you prefer, and not trimmed until winter.