Doors and Windows - Add window to wood door

I've googled with no luck - are there any pre-made solutions to add a window - or 2 small windows to a older wooden door? Or - a DIY tutorial?

Our doors are nice, solid wood doors. Maybe 35 years old. We just want to let some extra light into our foyer.

thanks in advance

Sure could. It wouldn't be very energy efficient, but your door probably isn't anyways. Pick out a size(s), have some glass cut, place and cut-out the desired openings, rip down or find desired stops/moldings to hold glass in door, and finish to match. This will all be much easier if you take the door off the hinges to work on. Good luck.

If it's a flat door, 1 3/4" thick, you can order the same glass that they put in steel doors. They come pre-attached to the outside plastic frame, you screw through the inside frame and sandwich the door between them. They don't come with screws, or they didn't, but you can find some the right size.
All you have to do is measure the size hole required and cut it with a jigsaw. The outside frame normally has a sealant pre-applied to a groove on the inside edge.

Most any Big Box or independent door and window company could order them.

If it's a paneled door, thats a whole different matter as the panels are not full thickness.