When I am sketching, at least 1 extruded piece seems to always end up above the vertical base. When a piece is higher than others, it has trouble printing with the others. I can use “front” view to visually lower the object to what I think is the base, but it isn’t always actually flat.
Is there a way to select an object and make it rest at z=0 ?
Joe
I have been drawing a sguare, extruding it negative so it extends below the z=0 line. Then using “align” to place object on the face of the square i drew. There is a tool to make a line horizontal or vertical. I wish there was a tool that would place an object at the z=0 hieght.
Totally agree. And if you align with the square it shifts not just in z but in x & y to align with the centre of the square. Not a problem if you only have one object but the shifting in x & y can mess up the alignment with other objects. All the user needs if the option to restrict the move to z, y or z. As I’ve banged on for years, TinkerCAD has solved the problem of aligning in whatever way you wish, with a very simple tool - but alas the developers apparently know best 
And please don’t tell me to use Translate … ahhhhhh!