A themed room only works when the structure is doing part of the job, and a hangar-style room reads as a hangar because the ceiling is honest about how it is held together. Bolt a propeller onto a drywall box and you have a theme. Leave the frame visible, run the lighting off it, and you have a room.
Which is why a room like this tends to make people want a smaller version at home. Usually it is a garage they have stopped parking in, occasionally a detached structure out back, now and then a covered patio meant for live music at a volume the neighbours will tolerate. The instinct is right. The scope is almost always underestimated.
A detached structure is a permitted build, not a long weekend. Foundations, setbacks, power, and whatever the local rules say about a second structure on a residential lot all arrive before the fun decisions do. Sound is its own line item and it is the one people skip. A room built to hold a band is a different room from one built to hold a pool table, and you cannot retrofit the difference cheaply. The same goes for the doors. Everybody wants the wall that opens, and nobody costs the header and the track that make it possible until the framing is already up.
The kind of builder who handles this works design-build rather than pricing somebody else's drawings, because the shape of the room and the way it gets framed are really one decision. Kingdom & Co works on casitas, additions and expansions around the Las Vegas valley, which is the bracket a backyard structure falls into whether it finishes as a guest suite, a workshop, or a bar with a roll-up door for one wall.
If you are sketching one, start with the ceiling and the door track. Those two decisions set the ceiling height, the span, and most of the budget, and everything anybody notices about the finished room follows from them.