I turned this walnut bowl a while back and funnelized it. As you may recall:
I ended up gluing a scrap chunk of quilted maple to the bottom and making it into a foot.
On the inside of the bowl, I was unable to get a good clean transition from the dark walnut to the light maple. Since the edge of the existing walnut was feathered into the maple, and things weren't exactly centered when I re-chucked it all, I just couldn't get it looking right. I ended up trying to hide the plug with black enamel paint. I poured the paint in about 1/8" deep, hoping to bring the level of it high enough to make for a clean "joint" between the black and the walnut. It looked OK, but after about 3 weeks, the enamel is still pliable, and anything left on it for long enough makes an impression in the surface of the paint. In the true spirit of "if you can't fix it, bury it", I decided this would become a chip 'n dip bowl. I turned another walnut mini-bowl to sit inside of the bigger bowl. After leaving the little bowl in place for a couple of days, the black enamel now has a perfect imprint of the foot of the small bowl, and the little bowl it fits nicely into the depression in the enamel.
It's the cheater's way out, but it's better than hanging the donut on the wall of the shop as a reminder. The wood was too pretty to waste.
Sometimes it's not the mistakes themselves, but how you get out of the mistakes, that counts.