After adorning the Christmas trees of a colleague and my own home with them, I can attest that a serviceable HST in about 1/144 scale can be made from a large thread spool, plastic 35mm film canister (now becoming obsolete), two popsicle sticks, large paper clips, gold paint, and aluminum foil. (Don't throw away the canister lid). Silver paint helps for the primary mirror, and of course one can get all carried away with secondary supports.You even get to point out that it's such an exact depiction that the primary mirror is not an exact paraboloid

Have you seen the paper models (like NASA's "Great Observatories" kit booklet)? Warning to onlookers - they are a lot more time-consuming and pretty addictive. If so, that would account for the Lego query.