I tried one on once at a hole-in-the-wall samurai museum in Tokyo. It was pretty hefty but very well-supported - my head didn't feel wobbly or strained.
It's one man's work of passion. When I went, it was quiet enough that an attendant guided us around the entire first floor personally. It's not exactly tiny, but it's just two narrow floors behind an unassuming frontage, and so a big change from the other (public) museums in Tokyo.