Kickstarting the trend, Shah posted a photograph of herself perched on her baby pink stairwell decked in Ganni checks.
"The #instarainbowchallenge is here! @talliwall and I are turning our grids into the #rainbowofhope this week as (we both live in Art Deco rented flats and so can't paint on our windows) and wanted to spread some joy and shake up our home #ootds too," she captioned the image.
"We'd love you to join in with us just tag us and use the hashtag above. Today is for all things ❤️ red! It could be your nails, socks or even a scarf! We can't wait to see your little bit of rainbow red today. Have a lovely day x 🌈🌈🌈 #rainbowofhope #heartzeenawears #ootdathome #ganniwfh."
In a similar fashion, Wall shared a snap of herself in a rainbow-emblazoned knit, jeans and work-from-home-friendly Converse.
"The line between workout wear and lounge wear has become increasingly blurred (read: nonexistent) round these parts," she admitted. "If you feel the same and fancy the challenge, I’ll see you on Monday! First colour: red."
The movement was only scheduled to take place for a week but with an influx of participants, there's no time like the present to join in.
Whether you're trotting to the local supermarket in your latest shoe purchase or spent Easter weekend lounging around in a breezy smock dress shouting for Instagram likes, it's something we can all get involved in.
We've rounded up our favourites below.
This article originally appeared on InStyle Australia.