No instructions, had to take it apart a few times to get everything together. tolerances are a bit tight, batteries get stuck and have to tap it on the table to get them out.
there's a photo that helps with assembly in the product description.. it's hard to see because it's like 9 pictures in a collage instead of individually. but it helps a lot.
I had a problem with one of the sorting locks being a bit hard to get on. all the rest of the parts were tight fitting. I printed mine on an A1 Mini. only trouble I see with it is the slot for the positive side of the batteries is a bit tight so maybe it'll get better with use, but I still have to give them a bit of a push down the slide sometimes.