Holey Brace Design
 

This is what I have come up with in the spirit of what suggestions and pictures I've seen here and trying to avoid symetricalness and even measurements. I'm not sure how much more needs to be removed from around the basket and magnet area if any. The holey brace is lined up with the basket frame.

Crimony!

I take it that's a sub? VERY nice work. You're in very good shape.

I'm building two 6cuft enclosures for some Selenium 15PW3 ProStyle woofers. Is it ok that the brace is so close to the basket or should I relieve some of that area?

Very nicely done indeed.

Some people advocate using bracing and support around the magnet itself, a tightly fitting hole, to take some of the strain away from the front baffle.
Haven't had the skill or patience to try it myself, from the picture you certainly appear to have the relevant skill and patience.
Good work

Very pretty.

I do like to have a bridge directly from the back of the driver to the back of the box that is solid.

Yours has a pretty sturdy looking split bridge which is probably just fine for a sub.

dave

It's very elaborate work, not really necessary. I just cut holes or rectangles. Agree with Dave re a solid brace to the rear.

The hole directly behind the magnet is for the voice coil vent in the center. The rest of the design was done mostly freehand to keep it irregular.

If you mount directly to the magnet, I would suggest compressing some rubber or something there, or perhaps some dots of silicone, to reduce the chance of rattles with expansion/contraction.

So when I install the woofer for the last time put a little silicon where it will meet the brace to keep everything a little snugger and hopefully prevent any rattles? There isn't enough room to compress any weather stripping.

If you put a little petroleum jelly on the woofer magnet it may help in the removal process.

Unless; of course; you definitely want this to be permanent