In Illustrator, you can create a dst file by selecting File > New > dst. In the dst file name field, enter a name for your new dst file. For example, if you want to create a dst file called “my_dst”, enter my_dst in the name field. Next, in the File Format field, select the .ai format. In the Size field, enter a size for your new dst file. For example, if you want to create a dst file that is 10MB in size, enter 10 in the Size field and click OK. Now that your new dst file has been created, you can use it by selecting it from the File menu and clicking Open.