jwk matcha's bottom housing is identical to fff's.
previously when i read about nylon bottom housing, i thought all were the same as cherry mx, or sp-star meteor. as it turned out that nylon is a generic name, and the devils are in the details. the nylon that cherry mx use is different from what fff and matcha use. hence, the typing feel and sound are actually different.
to differentiate them, nylon used for bottom housings of fff and matcha (and h1) is called polyamide.
jwk epsilon is ok as well.
edit: while the housing is identical to alpaca, the stock spring of jwk epsilon is 68g long progressive. it's not 2-stage progressive as described in the switch specifications. (or, maybe i was confused with the description, and thought it was a 2-stage)
this type of combination has a higher starting force, but it has relatively 'softer' during key travel.