There's plenty. The vast majority of the 'shell' would be solar concentrators - basically aluminium foil or something like it. You can make a LOT of that by dismantling a few asteroids, never mind a planet or two. Isaac Arthur's youtube channel goes into this in some depth (and is generally excellent, IMO). Here's an episode on Dyson Spheres: ▶ this video
in “Upper limits on partial Dyson spheres in the Milky Way” · View on HN