LEE filter holder & FORMATT Deep red Filter issue

I have a LEE filter holder (foundations?) that holds 100mm filters.

I also have a FORMATT/HITECH 100mmx100mm Deep Red filter.

The deep red filter is about twice as thick as normal 100mm filters, and as such will not fit in the LEE filter holder. It is too thick.

How can I get it in? Do I need to take the filter to some glazier and get him to bevel the sides down? Or is there some way I can make a gasket to make the filter holder accept it?

Any ideas?

lee spacers for 4mm filters:http://www.bhphotovideo.com/c/product/87161-REG/LEE_Filters_G4_Side_Guides_for_4mm.html
BOOM!

sweeet! Thank Bill!