shows a one hour response time drop checker I made. Here is how to duplicate it.
First, you need to go to Ebay and buy an acrylic dome. Search Ebay for "acrylic domes", and look for the 3" diameter ones, which are first on the list today. The minimum order is for 6 of them for less than $10 shipped.
You need a slice of one of the domes, about 3/4 inch thick, running from the top of the dome to the opening at the bottom of the dome. I'll add a photo when I make another one.
I made this cut by first making a miter box out of some scrap wood, that let me jam the flat end of the dome against the bottom, and the side of the dome against the end, and one side of the box, with a front side attached so the dome just fit inside. I used a hacksaw with a fine blade to first cut a slot in the miterbox to guide the blade, then cut the dome.
The "left over" part is: It's big enough to cut another piece from it.
For the remaining parts, you need some 1/16 to 1/8" thick clear acrylic, which is sold as glass replacement for picture frames, at most hardware stores. If you can find white acrylic, of about the same thickness, that is best for the tray that holds the drop checker fluids, but you can also paint the back of some clear acrylic with white fingernail polish to make your own white acrylic. I can get the tiny amounts of acrylic I need from Tap Plastics free.
And, Tap Plastics also sells suction cups. I use the 1 3/4 inch size that comes with a steel "S" hook attached in a groove in the stem of the suction cup. These are perfect for this project. As I recall they sell for 50 cents each.
So, I'm off to make a few more of these, take some photos, and continue this.