Jamieson, Fausset and Brown on Hebrews 1:10

10. And--In another passage (Psa 102:25-27) He says.

in the beginning--English Version, Psa 102:25, "of old": Hebrew, "before," "aforetime." The Septuagint, "in the beginning" (as in Ge 1:1) answers by contrast to the end implied in "They shall perish," &c. The Greek order here (not in the Septuagint) is, "Thou in the beginning, O Lord," which throws the "Lord" into emphasis. "Christ is preached even in passages where many might contend that the Father was principally intended" [Bengel].

laid the foundation of--"firmly founded" is included in the idea of the Greek.

heavens--plural: not merely one, but manifold, and including various orders of heavenly intelligences (Ep 4:10).

works of thine hands--the heavens, as a woven veil or curtain spread out.