This one is all about color, or to be exact, half way through it, because there's nothing like a playful color treatment to lift the spirit up. And guess what? You can try them all as quick DIY paint projects!
Oliver Jeffers, whose Instagram account, by the way, is a source of optimism, creativity, and comfort these past months, has begun in November 2014 a series of performances where he dips his own fully painted portraits into tanks of enamel paints.
Here you can find a DIY tutorial on making your own dip-dyed painting.
If you have old, tiered chairs, you might consider dipping them in paint. Although I think that these specific Thonet chairs are holly, and any DIY involving them is a blasphemy. But other than that, It's great.
Shai Akram and ZAndrew Haythornthwaite of Studio Alt Shift have designed and installed this series of tables and benches with padded legs, protected by heat shrink "socks" from future wear and tear.
And how about painting only half a wall? In this Barcelona apartment renovation by Colombo and Serboli Architecture, the lower half of the walls (& doors!) was painted a different shade, forming an "artificial horizon" to visually widen the vertical proportions of the room.
Last, but definitely not least, in my post about designing within a budget I suggested buying simple wooden furniture, and since some might find this option boring (quoting my 5 & 8-year-olds), there's always an option to transform it by dipping it in paint, like with this IKEA's basic dining set. You can even choose multiple colors, but if you do so beware, your kids will probably have a concrete reason to constantly fight about. Oh, who am I kidding, they'll fight anyway, but at least you'll have nice chairs to sit on.