If you are in the UK I would suggest trying to get a hold of a Paxman fixed bell case. Looks very similar to the John Packer. Heck, could be the same. But, I've not used a John Packer. I have used the Paxman case with backpack straps and have used it for almost all of my horns. (One is just to large a warp to fit). But it shouldn't be an issue with the Hoyer. The case has been through many border crossings and taxi cabs rides, in pits, behind stage flats, lots of opportunities for abuse and it has held up well.
Again, if you are in the UK you might contact Luke Woodhead. He knows just about everything about Horns.
+44(0)7970 971520
Luke@woodheadhornrepair.co.uk
http://www.woodheadhornrepair.co.uk/
Camden Address:
Woodhead Horn Repair
c/o: DOTS - The Camden Music Shop
132 St. Pancras Way
Camden Town
London
NW1 9NB
http://www.dotsonline.co.uk/map/
Ampthill Address:
Woodhead Horn Repair
33 Ashburnham Road
Ampthill
Bedfordshire
MK45 2RH
+44(0)7970 971520
luke@woodheadhornrepair.co.uk
http://www.woodheadhornrepair.co.uk/
