Well, I have made a few of them just with what materials I could find on hand. I do have screws holding the containers on, the tape is just to keep the strain off of the the plastic where the screws contact the plastic. The type of fertilizer(grain size) normally determines which I use.


Used this one today, being I was fertilizing larger established plants mostly. I prefer using the slot most of the time. I cut the slot too wide originally but just used some tape to narrow the hole a bit.

The one with the blue cap has two sized holes that can be selected. If several of the same containers could be found, the lids could be removed and cut differently and could be used interchangeably so one handle could be used. The knob on the handle just happened to be a flag pole, but I do like using it.
Edited to add:
I have a two gal. plastic container with a lid that I mix the fertilizer in. Fill it about two thirds full, then I can shake and turn it to mix the fertilizers together before pouring some into the small plastic containers. The small "dispensers" hold two tin cans full of fertilizer, an amount I find easy to deal with. I do carry the large container with me down to the garden to make refills quick and easy.

Great work-arounds Larry, so sorry to hear about your bad back though.

I use water soluble fertilizer. I mix it up in a 5 gallon bucket next to the outside faucet, then attach a Hozon applicator to the faucet. stick the Hozon hoze into the fertilizer bucket so the end of it is at the bottom. Then have fun watering your plants. You can mix in rooting hormones, and other additives (so long as they do not precipitate out some of the fertilizer ingredients). Here's the link to the Hozon: https://www.amazon.com/dp/B003TPBF1Q/
I used to mix a combination of various things and hand apply to each plant. It got to be too much when my hips started to go and need replacing. That's when I switched to this method---and never looked back (even though I get around fine now). I am getting as good, or better results than I ever did previously. I can easily fertilize any plants on my property with little effort in preparation, and the only work involved is dragging the hose around.
My favorite fertilizer for the daylilies is: https://www.amazon.com/dp/B008JSIKCU/

Larry, I also suffered from a bad back for years.
Tried everything I could think of. Lotions, potions, heat-pads, stretches, posture re-aligners, pain drugs, hypnotherapy, plug-in back massagers, pain-relieving waistbands etc. I spent a fortune.
Then one day I had a sleepless night of tossing and turning and my back was awesome the next day.
Threw out the old mattress for a 6" memory-foam one, and made sure I adjust positions several times a night since then. Plus got a nice firm sofa with a straight back (chesterfield type) and voila, no bad back for a couple years since then (fingers crossed).
Sofas that discourage slouching are almost impossible to find thesedays. We have become a nation of slobs. Looking back to ye olde times of even 50-100 years ago people had such amazingly straight postures.
Good luck with the back. I am 100% sympathetic. One thing I never got round to trying was the TENS system of pain relief. Unfortunately it just removes the pain, but the underlying problem remains. https://www.amazon.com/s?k=ten...
And thanks for sharing your inventive ideas.