The Coolest Pen :>

assembly skip step 1 for bic version
1 glue the tip to the main pen part thing(on both ends there are these groove like things. On one end they are longer (You need to glue the tip to the shorter groove end)) 
2 put the “pen writing thing” inside 
3 put the cap on( glue is optional if you want to replace the “pen writing thing”)

Very describing description right?

Also i give you a STEP file to do whatever you want with it.