@dyuonn.bakker
working with this sample list:

lets init an empty datatable and retrieve the length of longest array within the list

Lets add datacolumns of datatype double to the datatatable - as many as we do have items in the longest array


for the column name we do use the index output from for each as well
lets create the row itemarrays and add the datarows to the datatable:

Result:

find starter help here:
ListDoubleArray_VariantLength_ToDataTable.xaml (7.5 KB)