"Uni-kun", Japanese Uni (sea urchin) opener (updated)

thingiverse

A 3D model based on the widely used **"Uni-kun" sea urchin opener preferred by Sushi chefs**. Prices in the United States for this tool online hover around $70, while this can be printed for approximately $5 worth of plastic. Since I didn't have access to the original tool I used as a model, pictures of it from the internet were used instead. This model is not meant to be an exact reproduction of the original tool, but certain features such as its overall shape and length are expected to be close. The **pivot hole has been designed to accommodate a 5/16" diameter bolt**. A recent update added spring retainers on each handle to fit a compression spring. I used a 2-3/4" x 3/4" OD x 0.062 compression spring found at my local True Value hardware store. For those who have already printed the older design, separate STL files are provided here so you can print just the spring retainers themselves, saving valuable print time. Just use your favorite glue or epoxy to attach them to the handles. Note that due to slight geometry differences between the two handles, the spring retainers (left and right) are not interchangeable with each other. I've uploaded **five different STL files** of the same design. Two of the STL files represent each of two handle pieces w/the spring retainers while the third STL file is if you'd like to print the entire tool as an "assembled in place" print. (The design incorporates 0.5mm of clearance between their mating surfaces. Please determine if that is enough clearance to work for your printer.) The final two STL are the spring retainers (left and right) to glue or epoxy into the handles if you have already printed the older design. Note that I have yet to use this tool, so I cannot say if it is sufficiently strong enough for the task, but by all appearances it seems extremely rugged.