Smol Rocket Fin Jig

This is a mini version of a larger design of self centring rocket fin jig. You set the jig up using a pair of fins to set the bars distance and then you can mount the rocket tube underneath in the centring V slot. If this is a little hard to imagine it works in exactly the same way as the larger version I sell a kit for over on Tindie and there is a video showing how this works there. 

https://www.tindie.com/products/concreted0g/short-kit-rocket-fin-jig/

This little one works really well, you can work with Bt5 tubes or smaller up to bt50 and beyond up to around 32mm diameter tubes. You'll need some short 75-80mm M3 rods (you can buy long lengths and chop it up) and some M3 nuts and 4 12mm M3 bolts. The sliding bars need to be printed at 100 percent infill to make them as rigid as possible. I printed in Prusament PETG but any filament will do. Finally you need a couple of small rubber bands to thread through the holes in the end frames to hold the tubes in place.  I've supplied the stl's of the two components (you need to print 2 of each) and also uploaded the FreeCAD files if you want to remix it.