they used to sell them a long time ago havent seen them since 90', i made my own using a ruling compass. yup theyre real o rings it was a budget thing.
same color different bases and updated graphics. i decided against scratchbuilding new blinds inside the window.
and for my next trick a Gseeds inspired build
did some subtle changes like BMF instead of aluminum tape and nail polish green instead of that crappy testors candy green. the tires were made since white wall o rings no longer exist.