This is for my 28mm ACW project. I was thinking of the Build Something contest, but when the creative juices are flowing there is no holding back.
Gas wagons are scratch from Evergreen styrene and some 3D printed piping. Wheels will also be 3D printed. The balloon was made in 3D Builder in Windows. The lower portion was 3D printed but then heat deformed and some Milliput added to give some texture. The basket was modified from a part on Thingiverse.
Plan is to depict the balloon floating just above a tree line. Some tethers to the ground and the vertical rod painted sky blue should obscure the supports. (The project is too big for my usual background sheet. I have lightly blurred the backgrounds to eliminate some distracting backgrounds.)
The neat thing about 3D printing is you can easily vary the size, so a 15mm version is not far behind.