i have worked through some of the glitches and limitations (software and my own!) to create a model that is slicing properly. however, i want to be able to copy / paste to stack the model so i dont have to draw the entire object. on the right is a single model sliced how i want it, and the left is the same model stacked on top of itself then sliced into....randomness. has anyone else come across this or have any ideas?

In sketchup I usually make each piece into a component.  Select all the faces and edges for a piece, right click and make component.  Then I make copies of each component and lay them out flat on the Z origin as they would be printed.  Then I make other copies of the components to make an assembled model in sketchup.  Nice thing is  you can modify the components in your print pieces and it will also modify it in your assembled model.

Also having components makes it easier to select only one piece to export as an STL.

i will look into that and refine my modeling. in the meantime....

https://www.youtube.com/watch?v=0crmjken9fQ#ws