Worldbuilders can struggle with creating realistic-looking landmasses, be they islands or continents. Oftentimes this is because those landmasses are over-designed and come across as forced into being rather than arising naturally. To avoid this, sometimes the best way to design a landmass is to allow for a little randomness. Alternatively, one can look towards already naturally occurring forms to provide inspiration. The following methods draw from both of these approaches and can be used by worldbuilders who are grappling with creating realistic landforms.
Tie a string or shoelace into a circle. Toss it lightly onto a flat surface. The string becomes the borders of your new landmass. Any loops become either islands or lakes.
BOUNDARY WATERS METHOD
Find a map of the Boundary Waters or other lake & island rich region. Choose either a small lake or island and trace its borders. Those borders become the edges of your new landmass. Rotating the map and/or combining multiple such regions into a larger one can create completely novel regions.
Fill a bowl or bucket with soapy water and observe the aggregations of bubbles that occur on the surface. Model your landforms after the patterns you find in the soap suds. You may need to play around with the soap content to get the level of bubbles correct.
After you’ve got the major shape of your landmass figured out, small tweaks here and there can enhance it. You can also add additional features you want to include such as lakes and smaller islands.