I like Japan leather knife very much, it is really handier than utility knife when you cut leather.
If you don't good at sharpening knife, the replaceable knife becomes a good choice. But the OLFA plastic handle knife must use its owned blades, and the price of the blade is about 1.5$ for each piece. The cost is too high.
I figure out a way to solve this problem:
The knife I designed can use 18mm utility knife blade, each blade can be cutted into 3 short pieces and fix on it. And the price of the utility knife blade is very very cheap, only 0.1$
For quality insurance, I used solid brass as main body, stone washing and oxidation tech to prevent rusty, the handle is black walnut, what's more the crews are all brass gold-plating. I wish when you see it, you think it is an artwork.
I will gift you a piece of allen driver and 20 pieces blades if you buy this knife.
You can get 18mm so easy in your local market too.