Large pot or basin
Large decorative stones
Small decorative stones
Two sticks of bamboo
Sugru or some other type of sealing goo
Drill, drill press or Dremel
Step 1: Preparing the Small Pot
Once you've got your pot, drill a hole just a little larger than the outer diameter of the tubing that comes with your pump. A drill press is ideal here, but if you don't have one you can get by with a drill or dremel. Clean and sand the area around the hole.
Step 2: Insert and Attach Tubing
For this latest attempt I tried using Sugru, which cures as a pliable silicone and should form better seal (it's only been running for a few hours, so I'll have to update this Instructable in a week or three with how well it has held up). One worry I have is that Sugru apparently isn't good at attaching to brass, but so far the seal seems to be holding up.
I just used one 5g packet of Sugru, split it into two pieces, and packed each piece around the tubing with one on each side of the hole. Dip your fingers in soapy water to keep the Sugru from sticking to them instead of the pot and tubing, and be sure to completely seal the hole.
Step 3: The Rest of the Fountain
The next step is building a cradle for the pot. Take two lengths of bamboo and cut them down so they can lie across the top of the basin with a little extra extending on either side. A notch in each end of the bamboo will allow it to fit over the edge of the basin and hold it in place. That will give you a steady platform to lean your pot against so you can set it to whatever angle you want. I did this with the rear stick, but left the front one un-notched so I could move adjust the pot easily. The bamboo alone is enough to hold the pot in place, but it's easier if you stack your large rocks to where you can rest the pot on them as well.
Finally, fill the pot with enough small decorative rocks that the hole and tubing is completely covered, making sure none of the rocks are small enough that they'll get into the tube itself.