Put the support bars on the inside and put dividers in to hold paint, brushes and materials. Something very similar has legs that fold out for painting outdoors (Plein Air). This design would be for indoor use, particularly in a room that is only occasionally used for art. My wife has taken over the sunroom for her studio. Art's everywhere.
I wouldn't want one with folding legs, if you are not on a flat surface, it would rock. In fact, if used one very often indoors, I wouldn't. It would take up room on a table, and if you ever wanted the space, you would have to take it down, put it up, repeat. I would rather have a small table top easel, and a box, with a handle for the paints. Thinking on it, I wouldn't want this at all, I'd much rather have an easel, one where you could adjust the height for different size canvases.
Don't know what type paint your wife uses, but all I use anymore is acrylic latex, get it in the small cans. I get the basic colors, red, yellow, blue. Supposedly you can mix all colors from these, but it ain't so, so I also get white, black, dark green, and dark blue. With the white you can lighten the dark colors. I keep them in tall, straight, medicine bottles. No matter how long they have been in the bottles, it is still easy to twist the tops off. I use smaller pill bottles for custom mixing colors. I've tried both oil and water based tube paints, costly, and mostly a pain to use. The latex paint works well for me.
"It ain't what you're told, it's what you know." - Granny Weatherwax
Gather the villagers, pitchforks, torches; we march at dusk!
Some days, the supply of available curse words is insufficient to meet my demands.
.....Call me a craftsman, artisan, or artistic, and I will accept that. Call me an artist and you will likely get a quite rude comment in return. I am not a @#$%ing artist.