I got an idea for a Kossel Mini Bedclamp from this item:
But since my Kossel Mini is made from 2020 Extrusion it didn't fit. It seemed as easy enough for me to try to replicate in 123D so I did it :)
A bit of tweaking and for me it works perfectly! As said it is for Kossel Mini with 2020 extrusion, Hexagonal Heatbed (AliExpres...) and 170mm/3mm Glass plate. Holes are for M5 screws.
What you need is 3x the parts. Attach the lower part to the extrusion, place heated bed and glass and align everything and screw down loose. Then one by one unscrew screws and place the glass holder on top and screw down again. Then one by one press the glass down firmly and the upper part agains the glass and screw down tight. It should hold everything just nice!