Rectangular Bolt Action Pen

This is a rectangular body bolt action pen I designed to use Pilot 0.5mm Black Ink Refill from Amazon.comhttps://www.amazon.com/gp/product/B019WDULFO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1Pilot 0.5mm Black Ink Refill (LP2RF-8EF-B), for Juice Gel Ink Ballpoint Pen, (LJU-10EF-B), ×5 Pack/Total 5 pcs (Japan Import) [Komainu-Dou Original Package]Just needs a pen spring from any old click pen.