To make circular boards, you can select any of our manufacturing options except “MiniBoard”.
The online help within the ExpressPCB layout program explains how to define the board’s perimeter. Look for the topic “Changing The Board Perimeter”.
The perimeter of the board can only be shaped using straight line segments. To arrange the lines of the perimeter in the shape of a circle, it is helpful to first place a circle on the silkscreen layer. Draw it using the Circle/Arc tool found in the side toolbar. Make this circle the exact diameter that you want your board to be. The yellow perimeter-marker in upper left corner of your layout can not be moved, so place the silkscreen circle such that this corner is on the edge of the circle. Now add additional corners to the perimeter (as explained in the online help), equally spacing them all the way around your circle guideline. You can zoom in to help you align each corner perfectly.