I have a Xikar twin flame that does a pretty good job and was only $40 or so. Mucho cheaper than a nice Dunhill or Dupont. I am a 0-5 cigar a week smoker.
IMHO I wouldn't add much more bracing than is already called for on the plans. The enclosures are pretty small and should be pretty resonance free with minimal bracing. That should help a bit in fitting the crossovers. Plus adding extra material to the box without taking it's volume into consideration might have a negative effect on the F3 point.
Also I would ditch the plastic speaker terminals. Nothing like building a solid enclosure then cutting a hole in it and inserting 1/8" plastic. Binding posts directly in the MDF or using some aluminum plates with minimal holes cut out would be a better route. There some nice Dayton ones at Parts Express which are not that expensive.
Are you doing the dowel brace or something different?
Yeah getting things set up to cut square is an art in itself. And I find that you have to keep checking to make sure things are true.
Word to the wise. Don't drop or iPhone into the toilet. Everything will still work except for the mic/speakers:palm: Thankfully everything was nice and solid today. Best Buy waranty FTW.