The box is relatively small, with the inside only 10-11" long. It does mean that I didn’t space them all that far from each other. But, I think they are a bit further apart than they appear in the photo. Still, I need to catch them before they get too large of root systems.
If I have one which doesn’t fit well in a pot, I think I’ve got some taller (18"?) square pots around that I can try. Rolling River nursery sends out tress in them sometimes, and I rarely toss out a pot, until they start breaking.
The Edding pens aren’t all that easy to find for shipment to the US. I thought I had some on Amazon, then noticed that the shipping was 50 pounds. I finally found a 3 pack on Ebay for $18 including shipping. Though only one of the pens is the white 8055. I ordered one, but if anyone has other (cheaper) suggestions, I’d be happy to try them out against the Edding.