Alan, I actually recommend cutting the 45 deg angles and dado on the table saw. But in another post http://forum.carvewright.com/showthr...ters-for-a-box I made a 45 deg angle for a member. He cut the boards and they fit.
To answer your question, I like to use biscuits for joining the edges, they hold the box firm while gluing. Another method is dowels, and splines. These all work great to hold the pieces as you get them ready.

On this box anyone that buys the box will have to make sure they have the wood attached to a carrier board or they may cut the pieces loose and jam the bit, thus breaking the bit.

I have a couple of unique boxes I have designed on paper, and needed a way to precisely build the box, that is why I came up with a better way to build the box in MoI3d. (not urns this time) I plan to do a video when I have time.

Note: in each of the urns I sell, I have instructions, they may be simple but it is a guide.