Bought a pair of TangBand W5-704S just for fun. Checked their data and used Ljudia's website to calculate a suitable box (9.7litre) .
For HFI used a cheap dome tweeters from Swedish electronic componente supplier ELFA.
From the calculated box size I order 19mm MDF cut to sized and glued the parts together, making the large holes with a hole-saw (hope I didn't burn my drill ...).
After using a 2-component putty for cars and considerable amount of sanding and another layer I was finished for some tinting.