I used a plane into the cross bar then the script polygon2spline. So there might be unclosed parts I don't know, anyway I went with the fill manually. ThanksWhere is your spline from? It´s either not closed or made from segments. Check the "info" about it.
But I guess you can make it editable and fill it manually if you have to.
Cheers
Frank
It won´t work with splines from that script in the extrude creator - but it´s really easy either to draw a new linear closed spline and let it snap to the points of the other spline or to generate 5 quads (cross-shaped) and let its points snap to the cross-spline - use shell tool for thickness afterwards. Or type "X" with an san-serif font in the text-spline object - make editable and linear splines and lest snap + Extrude-creator for thickness.
Cheers
Frank