You will need 18mm MDF to create the curve templates, 3mm MDF to form the curve and timber mouldings to clad the curve.
Plan everything out in advance and think about how you will construct the island. You may need to run a piece of MDF across the back of any cabinets to attach the mouldings to, so factor that into your design. Also keep in mind how you plan to construct the curve form, as you may need to trim down the middle rib to fit the vertical panels.
Once you have finalised your design, create the templates for your curves using 18mm MDF. Each curve form will need three templates to act as a top, bottom and middle rib.
Depending on the design of your island, you may wish to include a cabinet in the curved space - this can be achieved by using a 300mm deep wall cabinet instead of a base cabinet.
If you plan to include a cabinet, you will need to measure up your chosen cabinet and cut a cavity for it into your curved templates.
To assemble the curve form, cut vertical panels out of 18mm MDF (or any other sturdy board that you have handy) and screw and glue them to the top, bottom and middle templates, ensuring that the curved edges are all flush.
Bend a piece of 3mm MDF around the curved form and use glue and nails to anchor it securely onto the form. You may need to use clamps or weights to help keep the sheet pressed hard against the form. Once the glue has dried, take a second piece of 3mm MDF and bend it around the first one. Use nails and glue to secure it to the first sheet, applying a liberal amount of glue between the two sheets. Gluing the two sheets of MDF together will help hold the curve in the board.
Once the glue on the form has completely dried, trim and sand back any overhang.
Repeat this process for any other curves that you are including in your island.
Now you can fit your curves into place and secure them to any adjacent cabinets.
If you are using a sheet of MDF on the back of the island cabinets, cut and install it now.
Cut your lengths of timber moulding to the height required to clad the island and sand or finish them if required.
Attach the lengths of moulding to the island using nails and glue.
If your moulding will be next to any cabinets, start from the edge of the cabinet and work across from there. You may need to cut down a piece of moulding to get the corners of your island finished flush.
Once you have attached the mouldings around the entirity of the island you can paint or coat the timber to finish it, and install your benchtop.