Basically, you only have to please yourself.
For me, I'm more concerned with the image on the display. Not the image some stranger gets at a dark site.
But, by all means, if you browse Metals Supply Houses, you can find things like Brass, Stainless Steel, or any of dozens of materials to add weight.
Have some custom turned at a Machine Shop, and you'll have something truly display worthy that you can be proud of.
Who sez your custom weight has to be round? Go hex. Or get something oval.
Just remember, you'll have to move it around someday. ;^)
In the early 1960's my Dad bought a big Buick 9 passenger station wagon. He built a trailer hitch to custom mount under it, with a 2" ball, and a smaller 1 7/8" ball.
A guy at Lockeed chrome plated them for him in their plating shop.
Dad was so proud of his Chrome Plated Balls. He got a lot of miles out of joking about his chrome plated balls.
