You could do a double Lack but have one unit per hamster.The biggest issue with having pairs of hamsters in appropriately sized cages is that they do tend to fight,plus to make a large cage suitable for dwarf hamsters it would need things that pairs really can't have
If you could do a double Lack unit instead each cage would take up around 42-44 inches of length and 21-22 inches of width.However,you could save space by only making one have a lid and have the other essentially stack on the other.You'd have to make doors for the bottom cage though,but you'd already have to make a lid for a cage anyways.It would be more space per hamster though,as each would be getting a half square meter cage instead of if fighting occurs getting far less than that with a split Detolf!
As for making things work for each robo and any hamster really,there need to be plenty of hiding spaces with minimal open spaces.Focus on providing lots of enrichment though!
Something with the Lack units to keep in mind is you can just put mesh on the sides and make disposable cardboard substrate borders up on the outside just to keep substrate in.You could probably get expensive and make them from plexiglass/acrylic or something else,but really why spend more when cardboard would do just the same for far less
I think double Lack units would probably cost less than a Detolf as well,plus they'd be a lot easier to move around since they wouldn't be as bulky or heavy
