I checked my OEM box of short W-knocks, and the model number designation is WK-816. I have no idea if this encompasses all color variants of the short W-knocks, but since none of them have any model number imprints, this seems like a good baseline model number for the series.
Next, in the last image above, there are two “Rubber Glip” models next to the K-518s I mentioned earlier; these are K-703 specimens.
And as @drifand suggested, the square-bodied DOHC pencils are “Jibson Colleen K-525.” Both are very hefty pencils!
The green piece to the left of the K-518s is a K-514, and the aluminum + green piece to the left of it is a K-521.
Next, we move on to the Rubber Glip W-knocks on the right side of image 4 above. The one on the far right (with the unique tip design) is a WK-1033. (This piece also comes in black and green, though they are extremely rare.)
The 3 pieces to the left of it are the Rubber Glip W-knocks, and they carry the WK-1031 designation.
Finally, in his original post, @drifand has the blue W-knock labeled as WK-1051, but I believe this is incorrect. I have the same piece, and mine says WK-1035 on the back.
There’s also a WK-1036, as seen on the far left of @Raybonche’s image on Reddit.
As far as I’m concerned, @Gunther’s hairline piece (pictured above), @Raybonche’s WK-1036, the blue and green variants of the WK-1035, and the Rubber Glip WK-1033 are the coolest and rarest W-knocks from the Colleen Jib library.