So I had some ideas for drop checker designs that I wanted to make out of acrylic, but I don't have any right now. But it's raining out, and I'm bored so I made this one instead. Probably the easiest design I could think of, but with the small opening it's not going to be the fastest responding version out there.
1. Little glass container - $1.00
2. Clear tubing - $0.33 p/ft
3. Suction cup - Free from old heater
The glass container should be able to be purchased at a hobby store or general store. The one that I used actually came as a Scented Reed Diffuser that was purchased at Dollar Tree. Here is what it looked like incase anyone wants to look for the same one, just make sure that you wash it really, really good. Who knows what's in that stuff.
Clear Tubing from Home Depot or Lowes. Take your newly purchased glass container with you and find some tubing that fits very tightly in the opening of the glass.
Suction Cup from LFS I guess. Like I said, mine was leftover from a heater I'm not using anymore.
Put your Tubing in the glass container and cut off the extra. It should be hard to force it in there for a tight seal. Don't cut it flush with the bottom or you won't be able to get it back out when it's time to change your solution out.
Add Your Suction Cup
Fill it with your solution and stick it in the tank. (Sorry for the color, I don't have any solution right now so I just put Flourish in there so it had a colored liquid in it for illustration purposes)
There you go. A drop checker that costs $ 1.33 (additional for a suction cup), that anyone can assemble without any tools (technically you will need scissors to cut tubing). I'm sure it won't be the fastest to respond to changes because of the small opening, but it should work ok if you really need one. Plus I don't think it looks too bad at all in the tank personally. I hope to be making some that will respond quicker when I can get some acrylic.
Disclaimer: I am not responsible for the death or injury of you or any living thing within any radius of you or your drop checker.