Lego blocks isolated on the white backgroundFree photo 6223582 © Tomas Valenta, Bm Association - Dreamstime.com
At Comic Con back in 2016, Star Wars voice artist Ashley Eckstein wore a gown made from Legos. Pictures of Ashley wearing the Lego gown may be seen here, while workshop photos of Ashley's gown may be seen here. The small 2 x 2 Lego blocks seem to have been preferred for the creation Ashley is wearing.
If you think a Lego dress would be impossibly heavy to wear, think again. This CNet article describes the construction of a plain black Lego gown, made with 12,000 Lego pieces, that weighed only 7 pounds. Ordinary day wear in the late Victorian era often was much heavier.
Finally, Instructables.com has a tutorial on how to make your own Lego dress. The tutorial only makes a dress with a Lego-covered panel--not a dress that is completely covered with Legos. It may still be worth looking into if you like the idea of Lego Fashion.
Happy April Fool's Day!