All four knobs are made from a Cali Bamboo woven strand Eucalyptus flooring sample, which has a lot of iridescence.
Knobs 219 & 220
Knob 219 has been refinished, and did not turn out as well as hoped. It was supposed to be translucent purple-blue-turquoise with iridescence showing through, but ended up so dark it’s almost black. Knob 220 turned out a bit better, with alternate layers of generic superglue and fabric paint (Setacolor Orange & Raw Sienna). The groove in the top of 220 was filled with Lemon Yellow on top of Buttercup, when Buttercup turned out to be too dark. Kiwi neutral shoe polish completes the top finish.
Knobs 221 & 222
Knob 221 uses alternate layers of generic SG and Setacolor Crimson Red, with Fushia trim trim. Knob 222 uses alternate layers of generic SG and Jacquard Textile paint in Apple Green, with additions of Setacolor Moss Green, Pernod Yellow, Buttercup and Turquoise. Both knobs show some iridescence and are finished with a top coat of Kiwi NSP.
These knobs could have been better; a couple look a bit worse for wear, without any actual wear. It may work better to use a lighter wood and an airbrush with fast-drying acrylic airbrush paint. Anything good takes experiment and practice.