Easy. Locations of construction errors below the sand block (e.g. missing/weird blocks) = Locations of stars Spoiler: Video solution (no tricks required)
Cool, clean, cute puzzle. At first I kinda wished it was B on the sand platform instead of the pillar draggable, but then at the end (after I spent some time thinking how to get R to the win block ) I realized... Spoiler ...it's actually part of the puzzle.
@Logo @Ray Aznable @Denis Nazin Thanks for PCR! @Ray Aznable The stars are attached to the metal which are then captured by draggable pillar. The original technique was invented by @Denis Nazin in Playing Cards