Stronger is subjective. There may be custom or 3D printed ones but not aware of different third-party alternate design propeller guards.
That said, I find the OEM prop guards rather
sturdy after smacking the broad side of a barn or pancaking it to the ground - at least a dozen or so times.
How are you taking it on and off for storage? Are they showing signs of plastic flexing (e.g. white stressed areas)?
Few options to consider if you want to go this route. Flight performance will be affected.
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