I don't know if anyone has ever suggested or actually tried it but a good dome to use for a scratch built bucket would be the old school batting helmet that's no longer in circulation but still could buy. The kind without the ear flap on either side. The kind they gave away on helmet day at the ballpark (here's a picture). The helmet weighs exactly 5 oz. And it's light and sturdy even after bondo-ing or spackling so your bucket won't be top-heavy. It can be cut with a box cutter to extend it to fit WOF dome base template. And the best part is that you can get one on the internet for under $10 easy if you shop around a little.
I have not seen any thread suggesting this but if there is then kindly disregard this thread. Have a good day everyone.