When we got our African Soft Furred Rats, I tried to think of an affordable enclosure that was cheaper than buying a tank. We only had extra ten gallons laying around, and in my opinion those are too small for African Soft Furred Rats. After searching the internet for awhile, I came across these instructions and I fell in love.
My lovely boyfriend made it for us the same night we picked up the ASFs. It ended up taking all day, a lot longer than we expected, but he got it done. The only thing we did different was that we used the wire that was wrapped around the hardware cloth to attach the hardware cloth lid to the plastic, ensuring that the rats couldn't chew it.
Many people don't trust the enclosure due to ASFs remarkable chewing ability with plastic. I've only had one problem so far, and while it was a big problem, we've fixed it and now we're 99% sure that there is no way for the little buggers to get around it. When I would take the water bottle out to refill it, they would use that opportunity to chew the edges of the hole where the sipper tube goes through. Eventually, it was at a point where they could chew it even with the water bottle in. That's when we had some escapees on our hands. Luckily, I was right there, and I managed to catch the stinker with bribery.. AKA puppy food. I was lucky that it was an ASF and not a mouse. They are so much more calm and collected; less likely to spook and run.
Anyways, we fixed that problem by putting a square segment of hardware cloth over the sipper tube hole. Voila! Let's see you access an edge of plastic now, you sneaky little cuties!