Honestly, if your Syrian isn't freaking out, there's no immediate need to upgrade. You could always buy another 40 breeder for a dwarf, but if you're dedicated to doing a DIY I'd recommend the bin cage just becaue it's a lower bar of entry.
So just a couple hours ago, literally not long after making this post, I found someone selling a 40 gallon breeder tank she used for her turtles for way cheaper than the one I got at the pet store so I bought it sort of spur of the moment but I got a cage now! Haha hard part is over, I think. Well now comes figuring out the interior layout and all the stuff I'll have to buy to make it suitable for my future dwarf but the cage part is done! I was really starting to consider the bin cage but maybe that'll come later. I'd much rather have a nice glass aquarium. You're right about not wanting to stress out my Syrian if he's not stressed in his current enclosure. He seems to be getting adjusted to his tank now and I haven't seen any form of stress whatsoever (although he IS a ghost hamster so I don't see him much). I still provide a variety of different things for him to chew on, forage for, touch and feel, sand to bathe in, tunnels, huts, sprays, and bedding toppers.
