I have an old (x for 1933) Primus 96 that had no burner bell. Using the template and techniques mentioned here I cut out the 2D shape in brass sheet, but this time I used a mandrel to create the correct 3D curvature. Then brazed the sides, cut the slots and flared the top Then I cut and brazed the tapered collar onto the bottom of the bell. Cleaned it up and fitted it to the lipstick fitted the original burner plate and fired it up The tapered collar is a good fit on the lipstick and the stove runs well and maintains vaporisation. Another old 96 back in working order.