pro tip: gandalf wears a ruana cloak, which is hilariously trivial to make and honestly just a really good piece of clothing even in modern times.
just get a big piece of rectangular fabric (as wide as your armspan, and 2x as long as the distance from your shoulders to the ground), make a cut down the middle of the short side, to the midpoint of the fabric, then sew a reinforcement at the seam so it doesn't rip up when in use.

Then just pull it over your head and bada bing bada boom gandalf cloak