I have created/modified some tools for Katana, Wakizashi, Iaito, Shinken.
The tools are based on the ideas of https://www.thingiverse.com/thing:3198623.
The spacer/buffer prevents the nagasa and habaki (blade and brass collar) from being forced into the saya especially during transport. For different sizes you can easily scale the spacer/buffer.
The sticks make it easier to wrap the sageo.
To tie the sageo you can use
I prefer to work with 2 sticks but this is my personal choice.
The author remixed this model.