Use your favorite route to get to the intersection of Main (Rt20) and Moody in Waltham

go south on Moody (the only direction available)

Cross the RR tracks

Go another ~90' (don't cross the river)

turn left after the Enterprise Auto Rental,

keeping it on your left

Ahead, (~350') you will see two large red-brick buildings, the one on the left is marked "World Wide Building" up high. That's the building my shop is in.  The door by the loading dock is usually unlocked during normal business hours.

144 Moody Street, Building #4,  first floor, room #8

781.608.0900 (cell)

If you'll be there more than a few minutes, a parking pass is required.
They are very quick to tow un-permitted vehicles.

Looking east (inadvertant courtesy of the map service of superpages.com):