Hey, sorry for the late replies.
Ideally, I would want to draw the outline of a block (like what it looks like when you hover over it in game), except all the lines would appear in front of the block (and they would be more noticable, ect. The end goal is to make it easy for the player to select a block). This is a really quickly done mockup of what I'd kind of want it to look like when the player looks at a block. There is probably another way to do this.
I'll try to follow draco18s's reply and see if I can get that working. Thanks!