"Nuclear pasta" is a real astrophysics term for the interior of neutron stars, describing the various intermediate phases between discrete neutron-rich nuclei and bulk neutronium. Under the pressures partway into the neutron star, the neutrons organize themselves into short cylinders ("gnocchi phase"), long cylinders ("spaghetti phase"), sheets ("lasagna phase"), etc.
The glowing ball in the item's mesh is mostly shielding, surrounding a microscopic speck of the actual Nuclear Pasta material. A solid ball of Nuclear Pasta that size would weigh trillions of tons (more than a mountain range) and would immediately sink into the ground and tunnel into the planet's core. It would also require trillions of tons of material to make.
A Copper Ingot's in-game size is around 0.128 m3, which given that the density of copper is 9,000 kg/m3, means a single ingot weighs ~1,125 kg. Since 1,200 Copper Ingots are required to make a single piece of Nuclear Pasta, the mass of one can be determined to be around 1,350,000 kilograms or 1,350 tons (assuming no waste).
Since numbers that large are hard for humans to visualize, 1,350 tons is the just about the weight of 13 blue whales, or a fully-loaded 314-foot long Clemson-class destroyer.
With the density of Nuclear Pasta estimated at ~1017 kg/m3, the amount of actual physical nuclear pasta inside of the sphere would thus be ~0.28 mm wide, with the rest of the sphere being shielding.
When placed onto the ground or moving on a conveyor, Nuclear Pasta warps the space around it, which is true to real life, as neutron stars have enough gravity to bend light.