From that picture I could make you a key to the main door!
Making a key from scratch is actually quite an undertaking - you’ll need a lathe and a fine TIG welder, or else a way to drill and file and silver solder or braze the bit on (the bit is the part with the cuts on it.)
However, I’ve got lots of blanks that will fit. All I’d need to be certain is the actual diameter in tenths (or preferably hundreths) of a mm of the stem, & the highest lift cut, plus the width of the bit. Otherwise it might require a little filling to work.