Make yours just a little too short so they won't. Elbow-length sleeves with white cuffs. For some reason, the collar isn't quite attached for about the first inch on Magenta's right side but falls loose. The cuffs are a single white band of fabric folded up and over the sleeves. The short ends of the cuff aren't sewn together, forming a V-shaped gap.
Authentic cuffs fall down a lot.
A wise Magenta tacks hers in place. You'll have to make both buttons and loops. The easiest way to make the loops is probably to sew a long thin tube of fabric, then turn it inside out and cut it into sections. Mina Smith suggests making them out of double-folded black bias tape, which is easier but gives you less control over the width. Do not make loops out of anything that ravels, and make sure they are securely sewed onto the dress, preferably with at least two rows of machine stitching.