The only trouble with the homemade ones from the jug material is that they don't have the little step on them that'll hold the chain up and avoid it wedging down into the groove.

If you can't find one that is a multiple of your spoke count it's not a big deal. Just cut off the little tangs from the protector and drill for some small zip ties as needed to fit the shield.

I'm another believer in these simple guards. It's the nature of stuff like derailleur adjustments to go OUT of adjustment and it's cheap insurance to have the guards. I don't care how much it makes my bikes look like department store specials...

I had one bike where for whatever reason it overshifted and ripped out 6 or 8 of the spokes and bent all the rest. Never again.... NEVER again.