These are pretty simple and fun to make. Worsted yarn makes for a nice sturdy cuff-style bracelet. This is the pattern to make the bracelets look like the 1st year scarfs (the ones with the block stripes). Soon, I will post a pattern to make bracelets that look the the 3rd year scarfs (a main colour with smaller secondary colour stripes throughout)
I used the following yarns for each house:

The Yarn
Gryffindor (Red & Gold):
Red Heart Soft Solids – Wine (MC)
Bernat Waverly – Gypsy Gold (CC)

Ravenclaw (Blue & Bronze):
Caron Simply Soft – Celestial (MC)
Vanna’s Choice – Honey (CC)

Slytherin (Green & Silver):
Caron Simply Soft – Cypress (MC)
Caron Simply Soft – Heather (CC)

Hufflepuff (Yellow & Black):
Red Heart with Love – Daffodil (MC)
Red Heart with Love – Black (CC)

The POA version is now available! Harry Potter POA scarf bracelet