This sleek fiberglass case with removable and replaceable cover fits most euphoniums, with the exception of the Miraphone M5050, maybe others that are oversize. The smart retention system, shown in the pictures, holds the instrument by the bottom bow, preventing the bell from touching the inside of the large end of the case even when set upright on the on the bell end. It's brilliant.
Weight: 11 lbs
XL model fits M5050 fine. You'll need to remove three foam pads (Velcro attached), and the bell will be about 1" away from the wound bell end stiffening disc, but it looks to be safe inside there.
This case is designed as hand luggage. It's not designed for checked baggage service when flying.