Castrillo's prolific output of more than four decades includes not just nationalist and historical monuments but environmental art, abstract pieces in the round (soft and hard-edged), functional art pieces, art jewelry and body sculptures, liturgical arts, and hammer-out bar relief murals with strong messages of social issues.
“I never compromise my idea by conforming to the limitations of metal…despite the high technology involved in sculpture, I often have to innovate. The problem of making high sculptures is often in the area of engineering which could indeed by quite restricting. So I see to it that my aesthetics is not hampered by any technicality in metalcraft or in the construction of the metal structures.
I love the physicality of sculpture, the heavy duty labor that goes with into it and the challenges of taming the material, controlling the tough solidity of the medium and moulding it into something fleshlike, lifelike.
I always find something in metal that makes me relate easily to it. The creative experience takes on something like a gladiator in an arena, where he faces the opponent with a sense of trepidation, knowing that the opponent will not surrender without a fight. The challenge is there. And it is great. Then again, there is something beyond the “physical combat” with the medium. The challenge assumes metaphysical proportions. A man must challenge himself to the limits of his being, his talent, his spirit and triumph over the most formidable of odds.”