OK, here's what you need to make this:
2 liter bottle and cap (preferably a water bottle, smaller size will work)
an old hose (or airline tubing for smaller tanks)
pen or pencil
Here's how I did it.
1. I rinsed the 2 liter bottle and cap really really good with water.
2. I cut the bottom off the two liter bottle, and took the label off. (pictured)
3. I used a knife to scrape most of the sticky stuff off the bottle.
4. I took the napkin and put some rubbing alcohol on it and rubbed at the sticky strip.
5. I took the other napkin and rubbed it dry, it took some elbow grease but once it heated up from the friction it started to come off.
I repeated steps 4 and 5 until i got this sticky strip off the bottle. Probably took about 15 or 20 minutes.
6. Then I took my cap and put the hose to it and traced around the hose with a pen. (pictured)
7. I traced the line with my knife really carefully and lightly until it started to make a groove, then I applyed more pressure. Kept at it for about 15 mins and finally got it to come off with a pretty good cut. (pictured)
8. I put the hose into the cut hole on the cap, and screwed it on. (pictured)
9. (optional) Put silicone around the bottle cap and hose to seal it up for air tight gravel suction.
Pretty simple and pretty effective. I didn't even put any silicone around the cap and it works like a charm as you can see in the picture. I took one of it sucking up the grime, and another pic of it after it had already sucked it all up so you could see the difference. I haven't tried a smaller bottle yet but I take it that it would have more suction on a smaller volume of gravel. I could also see air line tubing being used for the hose for smaller tanks, and I've seen water bottles that were less than 12 ounces. Hope this helps save a good 20 bucks!