RE: tip-tanks fabrication
Use some plastic waste pipe of near diameter for the main body, put some balsa dowel on a drill/lathe WHY (make a mandrel if needed ) and turn to shape using a sanding block, glue into the waste pipe, seal the wood with thin cyano and use a little car body filler to blend in , ditto for the back end,finally, prime and paint. Drill to fit wing.........