Jeff, here's something you can make yourself. Actually, I used a cardboard version for quite some time, until I got fed up with having to tape it to the baseboard every time I did test strips
Then I finally decided to make a more permanent version.
The pictures will tell you everything you need to know:
The "base" can be anything: MDF, whatever.
The "ribs" are there to help you position the paper properly by feel, when working in the dark.
This is adjusted to my way of doing test strips - I use actual strips of paper, not full sheets - as seen in the third photo.
Let me know if anything's unclear