very basic assembly, if bolt(2) dosnt press fit into bolt(1) try sanding bolt(2) down or downsizing the model by 1% or so, otherwise all you need is a pen cartridge and a spring. I know pilot g.2 and similarly sized pen cartridges work, i tried spacepens but they need a spacer, idk abt anything else. 1x of all parts. PLA works but if you drop it, it goes full grenade with the spring and all so id recomend solid infill or petg, abs, ect