Gotta use what ya got!!! Having said that Poplar isn’t the bestest, it’s pretty soft. Side effect of being soft though it that when you run your spindle into it (and you will eventually), it won’t do as much damage. I’ve used wood, and plastic, and just a week or so ago went with 1/4" 6061 T651 aluminum plate. The plastic ones I made gave up at random times, but there’s literally a gazillion types of plastic and some may work better than others. Oak or some other hard wood, like Ash would be better. The plus side of using the aluminum that I finally used is that I could make my clamps thinner and lower profile. I will attach my VCarve file here. I used the 1/8" ZrN coated 2 flute end mills sold here at C3D. The extra holes in my VCarve file are drill holes for screwing the 8"x8" aluminum plate to my bed before I cut these. The holes in the ends are to be tapped with a 1/4-20 tap.
clamps.zip (387.0 KB)