Maybe this is possible? Trying to run molding horizontal along the top of tile above a shower surround and match it with a piece running vertical along each side of the shower. These are 90 degrees from each other on each plane - any trim carpenters out there that can help me with these cuts? Don't have a lot of practise scrap to play with. Thanks, Dan:confused:

For some reason I can't quite understand your question.
Are the vertical pieces in the corners? If you take a horizontal piece and cut a 45 degree angle, take the verticle piece and cut an opposite 45 degree angle, match them together and you form a 90 degree angle.

If you run 2 horizontal pieces into a corner, cut an inside 45 cut on each piece so they meet into the corner. Then if you have a single vertical piece in the corner, this only can butt into the horizontal pieces.

Am I close?

Thanks for the reply - but after ripping a bunch of scrap, have come to the conclusion that this is impossible with any dimension molding. Came close with 1X1, but can't make it with my " mini crown". Would have to send pic or very complicated drawing to show what I was trying to achieve.