I drive a 1971 VW Beetle and I did some upgrades to its engine. One of the premises I wanted for the upgraded engine was that the looks would have to be as stock as possible.
So, for air cleaner, I got some VW Brasília dual-carburetor air cleaner assemblies (which use Fram CA3130 paper filters as standard) and replaced the filter with a high flow compatible one that was supposed to be plug-and play.
However, the "stock" (aftermarket) air cleaner pan was quite restrictive due to some structural mounting points that covered about 45% of the intake tube, killing the airflow to the carburators and choking the engine in the proccess.
I did put some "sporty" conic air filters provisionally but the looks of that didn´t please me. So I went to the drawing board and designed an air cleaner assembly that did not have the sections that restrict airflow.
It´s still a work in progress, though. Will update this as long as possible. It´s still on test runs, so far it´s working good. I might make longer poles so I can add a taller air filter though.
This was made considering a standard Solex 30/32/34 carburator as those used in Brazilian aircooled VWs (52mm carburetor-to-filter fittings) and the Inflow HPF4005 air filters (similar to the Fram CA3130 but high flow, 143 mm (OD) x 98 mm (ID) x 57 mm height, but the design is completely parametric, so it can be adjusted in FreeCAD for any carburator/TBI sizes or different models of round air filters.
Unfortunately I cannot put FreeCAD files on Thangs, but feel free to contact me if you want to remix this design for a different carburator or air filter!
The design does NOT have a breather hose input as I use a oil catch can in my car.
For materials, PLA is not an option for obvious reasons,as it will surely deform due to the temperatures in any car engine bay. You should use PETG, ABS, ASA or Nylon (CF infused Nylon would be great for this).
You also need six M6x10mm hexagon-washer hex bolts (or, alternatively, Allen button heads with washers), and six M6x10mm heat inserts that should be put in both extremities of the poles.
Will add further images as long as the project goes.