Long XLR cables - DIY construction suggestions?

Hello,

Wanted to ask for recommendations for a DIY XLR cable designs suitable for about 40 foot run -- home use. Pre-amp to active crossover.

Any suggestions for a nice sounding design? Couple of notes to aide the thinking:
1.  I like the sound of BBQ Audio Duelund wire XLR cables that I have but they are ony 18' long. Situation changed. Also, they are a bit pricey. But sound so good.
2. Don't think I have too much RFI or other sorts of interference to worry about.
3. Don't like bright sounding cables. Such as silver based of any form.
4. I've got 900 ft. of CAT5 solid core teflon (plenum rated) wire, just in case.

thanks,
Herman