You might want to make friends with one of the watchmakers here, and convince them you have a vision. I'm not a watchmaker, but I'll help as best I can.
Usually, the Jules Borel parts database is very helpful. Go to
http://www.julesborel.com/products/watch-parts and launch the Watch Parts Database from the link in the upper right corner. Search in the format OME CS#KM6292 . No useful results for case tubes.
Next try Cousins UK. Go to
https://www.cousinsuk.com/category/filter/omega-case-parts and search 6292, select this model, select Case Tube, then Search All under color. Click Search for Items. Cousins gives part number 090ST0099 but won't sell to you, Restricted Item. They do give a part number though, which you can use to search eBay and whatnot.
There's one of these on eBay now. Again, I'm not a watchmaker, I've made mistakes with part numbers in the past, take this with a grain of salt. Ultimately, you'll want to consult a watchmaker.