Freestanding lace (FSL) is an embroidery design that is sewn onto a water-soluble stabilizer, which is washed away after the design is embroidered. The stitches in such a design must be laid out so that they support each other because there is no fabric to hold them (except for appliques, which may or may not be part of the FSL design).
Studio NEXT provides a loose fill that can be used as a background to secure the rest of the FSL design. It is called FSL Grid and is a type of Mesh > Net object.
Fill created with FSL Grid
The FSL Grid can fill objects of any shape, even those with holes. Several grid patterns with adjustable spacing and layer counts are available in the Parameters window.
A typical FSL design has a border made of satin stitches to hold the lace together. In Studio NEXT, satin stitches are created either with the Column tool or with the Outline tool in Satin mode.
Other parts of an FSL design can be digitized using the Outline tool in Sample mode, for example.
Remnants of the stabilizer make FSL embroidery stiff. If you desire more stiffness, spray the finished embroidery with stabilizer dissolved in water and let it dry.