I am building a large deck for my daughter and cost has become an issue. The balustrade now is to be made of atop and bottom rail with 40mm x 40mm spindle. The rails have insert fillers. I have seen 2 ways of doing the construction. One screws the spindles to a complete lenght of infill and then the whole is fitted to the rail top and bottom. The other way is to cut the filler into 100mm lenghts and put the spindles directly into the channel in the rails and use the filler as spacers. I used the latter method years ago on a small section down some steps but this is a much bigger task. To add to the problem there is a slight variation in the length of the spindles, 1 to 2mm. Any suggestions as which method you suggest. There are over 300 spindles!