I have sourced 3 covers over the past few years.
The first one was when I was still in China. That was for the 1.9m piano in the snooker room. At that time I was still in China. I simply ordered a cover by stating the length of the machine. It arrived and I brought it to Bulgaria. It fits fine. It isn't perfect but is entirely adequate. It is a sort of faux velvet.
The second one was for my C Bechstein B. That is a 2 metre long unit. A friend of mine is the son of a very skilled seamstress. She came and measured the piano, went off and made a first version. She brought it, stuck some pins in it and took it away. When it was returned it fitted like a glove. That one is made out of cloth nd looks very good. There is some white trim along the bottom edge and that has made the whole thing look really neat. That one is in the music room. It is made so that one can fold back the cover in the area of the keyboard and play without needing to remove the whole cover. That is useful as it is on the music room piano.
The third one is a bit different. I contacted a cover maker in UK who said he would send me a roll of paper for me to make a template. The roll of paper didn't arrive. (Thank you Bulgarian post). SO I contacted a cover maker in Sophia, Bulgaria. This firm was recommended to me by a friend who is a concert pianist. This one had to be the best of the lot. It is for the 9' Bluthner in the ballroom. The ballroom is largely unused except when I have a party so I wanted something that would really protect the piano. The firm offered various grades I had decided on the waterproof, unpadded but with a sort of flock lining to come down just below the level of the body of the piano. The price was extremely reasonable and I was about to say yes when the roll of paper finally arrived. So I cut out the shape and mailed it to the Sofia company. The cover fits like a wedding dress. I could not be happier. The only slight problem is that it really is a 2 person job to remove or replace it.
I hope that lengthy response will be of some help.