Well, some 8-10 years back I made my cab for my MT180D and it has stood up really well to the test of time.
Used 1.5 x 1.5 sq tubing for the frame, roofed with 16g galvanised and made frt and rear windows with 16g as well.
I went to a scrap yard and got 2 of the larger rear school bus windows along with the rubber gaskets for almost free as yards really do not want glass.
Also the bus donated a rear 'under the seat' heater for the project.
Mt roof and front and rear pannels are fastened using 1/4" sheet metal screws to the frame as I did not want ugly welds that would rust.
Galvanised sheet was chosed for no rust reasons as well as we all know that branches do cause nicks and scratches.
My sides are HD transparent plastic stock as used in convertable rear windows as I wanted full side vision.
Glass frt and rear was a must as I wanted wipers for snow removal work and plastics I knew would smear and scratch eventually.
After all this time of usage, there is very little that I would change from the origional design.
I did provide possibilities of remouving rear window for summer usage but have never done so.
Instead I made access door remouvable and added 2 fans to keep me cool.
Fans also sort of blow the bugs out of the cab and in winter keep windows defrosted.
While the bus heater is just fine, I needed to install rugs on the floor as the many slits, slots and anti skid holes just let in too muck cool drafty air.
My total cost was about $250. at that time.
Yes it is indeed doable, and I'd do it again.