As per subject line. Have checked the Bay, and found this for sale :-

Zetec bike carb universal inlet manifold kit

Has anybody else tried building/welding these?

Ive done it
I bought the more expensive ones - about £60
The cheap ones were'nt on at the time
If your ok with a mig its easy enough
I mounted the carbs to the tubes with silicon hose
Then tacked the tubes to the plate
That way you get the right spacing
I spaced my carbs for better port match and equal tube length
U2u your email and ille send you pics
Carbs needed a bit of faffing to get right but its flying now

The other (IMHO better) option is to respace the carbs and use proper bike carb rubber inlets. That way you don't need a manifold as such.

Have a look in my archive to see mine.

Stu

Thanks both for your replies. Will deffo look at your photo archives.