Gratings by Kelynd

You've got a good start here but I've got a few suggestions:

1) If you want, you can make those spokes equal thickness at all points instead of tapering in at the middle. (Check out http://www.filterforge.com/filters/6888.html)

2) Reduce the number of controls. I'm sure there's at least a few controls you can get rid of while still keeping a reasonable amount of customization here.

3) See if you can fix the normal map, when you have a hard edge (two opposing colors right next to each other on the bumpmap without any "smoothness") the normal map does not render properly. I would recommend mixing in the grunge of the surrounding plate as very very low opacity and then passing the whole bump map through a blur of .0001 see how that works out. It's possible to include grunge in the normal map while still retaining good depth but it's tricky- (here's my best example: http://www.filterforge.com/filters/6133-normal.html)

4) DON'T EVER EVER use frame, it breaks everything when you adjust size if you need to make circles (I noticed this at the end) try this technique: http://www.filterforge.com/filters/5392.html

Whether you consider my suggestions or not, nice looking filter- keep up the good work.

i like these. wouldnt be too much of a stretch to do manhole covers from here, too.