Article by hallin222 of the XLFORUM ¹⁾

A K&N filter is used with everything else being fabbed.
An 1/8“ aluminum plate was used for the material.

²⁾

Trace the filter onto the aluminum sheet (whichever filter you will be using).
Cut the piece with a jigsaw (best).
Other cutting tools work also but the rotary blades create more heat and will melt the edges.
In that case, cut outside the edges so you can sand back to the lines you made.
Drill the holes for the carb mount and smooth all the edges.

^{3) 4) 5)}

Drill two holes in the plate for dowels (spacers) for the front cover (also created from tracing the filter).
Cut a mounting bracket (this one is 1/4” thick) to mount across the dowels and tap the bracket for the size mounting bolts you choose.
Align the outside cover on the assembly and drill a center mounting hole through it.
You can then buy a long drill bit to assist in lining the center hole to the cross brace in the back.
Then tap that hole for the size bolt you choose.

^{6) 7) 8)}

Make sure you test fit along the way as it's being built. The bolts and spacers here made contact with the carb bracket.
It was later fixed with shorter counter-sunk bolts to sit flush with the back face to allow proper gasket sealing. You can leave the finish as it is, polish it, paint it or have it chromed.
Either way it'll be one of a kind.

^{9) 10) 11)}