Ok Bas I will do my best
He have cut two brass plates the same size like the bales.And then he has drill a 3mm hole in the middle off the plates and then take out the metal in the (sockerbit ...se pics don't know the word on English) who is also 3mm.After that he has soldering the metal part from the..sockerbit.. to the plate and put a 3mm steelwire (piano) thru the plates.Now you can fix it with the small screw on the ..sockerbits part.After that he has drill an other hole in the plate to fix the string (same that you use for real bales.)Now you can put it in the drill and add some glue for wood until it's full
I hope you understand mate \ \ :D :D