I’ve had the Grotto and attachments for a number of years now.

This is the most recently layout:

• The Grotto (main bookcase with six shelves)
• The Annex (secondary bookcase with two shelves)
• The Expansion Fort (formerly my cockatiel cage, containing the wheels)

The whole thing is connected with 3″ PVC pipe which leads out to:
The Playground (a big desk with toys for free range time).

There’s one problem I’ve consistently had over the years.

The pipe out to the playground dead ends with an endcap that I remove when it is playtime.

When my rats have reached senior status, I’ve noticed that they like to walk to the end of the pipe, but have been unable to turn around to go back.

I’ve invented a new term for this: marinade rat. If I don’t notice that they aren’t where I can see them, they stay in one place and, um, sit in their own juices.

Yeah, I know, gross.

The way I solved this problem in the past was to pay careful attention to them as they got older. When they reached potential marinade rat genre, I removed the PVC going to the playground and just capped off the connector between bookcases.

Unfortunately this meant there was no access to the Expansion Fort.

That hasn’t been a huge problem up until now because potential marinade rats are usually only with me a few more months. 🙁 Then I hook up the Fort again and everyone’s happy.

But just this past weekend, I adopted two sprightly youngsters from Mainely Rat Rescue.

The youngest is just over 9 weeks. They both really love running in the wheel, and should be able to do so.

I thought and thought about how to solve this problem. Then I realized: if Coral wants just to keep walking straight, I could build a turnaround at the end of the tunnel.

So $24 and a trip to Lowe’s later, here is my turnaround:

It has a cap that unscrews for Playground access.

As I type this, Twyla (one of my newest girls) has found her way out.

Coral has gone on a walkabout. I saw her pass the new opening out to the playground, glance out, but then keep walking past.

I just checked and she’s back in the Annex.

Now she’s walked past it twice, then came out on the 3rd lap, went back in, and came back out again.

I think we have a winner!

Here’s a video of Guinevere’s first time out, followed closely by Coral.