KZ440 Air Cleaner parts

I guys, I thought I might post this here instead of my project build. For the first part of this build I just want to get the bike running in stock form - it may or may not stay that way... Before I can get her running I need to get some sort of air filter on it. I have the Air box & I've just softened up the old boots so that half is good but I have no filter or holder, see below.

Maybe I could get one of these...

and figure out a way to hold it tightly over those 2 square holes. Or I could buy filter foam sheet and glue a few layers together. I can get that here in NZ for 30 bucks - might be a good option.
Any other suggestions out there?

Here's a KZR topic for making an aluminum airbox with photos & video. .... In case your idea doesn't work out.

Custom Air Box for KZ440. by V3DT

Found an air box (complete unit) but a little pricey






www.ebay-kleinanzeigen.de/s-anzeige/kawa...n/700849132-306-8136