While on the lookout for a more compact housing for the End Fed Half Wave matcher, I came across this perfectly sized enclosure at Altronics (Hammond 1551). At 50mm x 35mm x 20mm, it is just right to hold the FT-82-43 core, a BNC socket at one end and a terminal at the other. The case is just a bit too small to fit a banana jack as it would protrude too far inside, so a 4mm bolt, washers, nut and wingnut make the antenna connection. A 4mm nylock nut holds the wingnut from coming off.
The toroid is the same one as used here, with a 3 turns bifilar wound primary over a 24 turn secondary. A 100 pF and 45 pF capacitor are in parallel across the primary to improve the match.
This is quite a bit smaller than the earlier versions and is a better fit with the KX2 and antenna in the case. Total weight is 38 grams.