Mandrel for making coils out of 3/16 brake hard line.  Can be “unscrewed” from the bent line after forming.  Produces coils with 0.25 spacing out of 0.19 OD brake hard line.  Make up to 5 coils with a OD of 2.2 in.  Can use pliers to catch the keys on the inside to help extract after forming. 

Works well with NiCopp brake line (honestly, why would you use anything else?) but should do mild steel as well.  Good luck with stainless.  

Printed on MK4 out of PETG, 20% infil,