Ornamental borders made from stucco are designed to convey height (10)
I believe the answer is:
cartouches
'ornamental borders' is the definition.
(a cartouche is an ornate frame)
'stucco are designed to convey height' is the wordplay.
'designed' is an anagram indicator (designed with the letters).
'to convey' means one lot of letters goes inside another (convey can mean to carry).
'height' becomes 'h' (abbreviation in geometry).
'stucco'+'are'='stuccoare'
'stuccoare' anagrammed gives 'cartouces'.
'cartouces' going around 'h' is 'CARTOUCHES'.
'made from' acts as a link.
(Another definition for cartouches that I've seen is " combustible cases".)