Designing a modular kitchen requires careful planning and consideration of a few key elements. The thumb rule to keep in mind is functionality, style, space and budget. Firstly, consider the functionality of the kitchen and what activities you will need to do in the space. Secondly, decide on the style of the kitchen and select the materials, cabinets and countertops that best suit your needs. Thirdly, make sure to measure the space correctly and plan the layout of the kitchen in order to maximize the use of it. And finally, factor in your budget and make sure to shop around to get the best value for money. With these key elements in mind, you can create the perfect modular kitchen to fit your needs.