You will need...
55 x 150cm of bouclé wool
35cm of hook and eye tape (available here and almost nowhere else; to my knowledge they're no longer available at any mainstream retailers, perhaps because the hooks and eyes are fashioned from the ivory of unicorns and there's a shortage. Either way, it's not like the old days and sadly you have to look online. And breathe.)
Jacket sleeves (ideally lined)
Needle and thread in a contrasting colour to the fabric
Quite easyStraightforward in principle but it has its fiddly moments.
TimeA day. Mine took eight hours. I thought it would be more straightforward but a lot of that time was spent problem-solving and figuring out how to make certain things work - both of which have been taken care of in this tutorial, so it should take you significantly less time.
So, just to wrap it up...
Finish off any raw fabric edges with fray-stop glue.
NB: Make sure you pin the fabric to the mannequin with the wrong side facing outwards. Try to position your fabric as concentrically as possible so that the fallaway collar is symmetrical (if it isn't, you can just cut away the excess fabric on the relevant side and fix the edges with glue again).
NB: This hand stitching should be done - and the outer sleeves should be visible - with the right side of the fabric facing outwards.
NB: Attach the eyelets under the folds of the jacket opening and top stitch them in place.