Strut the shore this month in a strapless monokini from local designer Sinesia Karol. Born in Brazil, Karol learned how to cut and sew samples from her beachwear-making mother, and later took classes at Boston’s School of Fashion Design. In 2012 she started her own swimsuit line not in the tropics but right here in sun-starved Waltham, where she dreams up vibrantly printed bikinis and caftans sold at stores here and abroad. Especially alluring are anything but basic one-piece suits like this one, which features an all-over textured floral pattern and asymmetrical cutouts. “They don’t have to look like Speedos,” Karol reminds us.