What size tubing would I need to make my own rope lights?

Yes yes, ready-made rope lights are common and inexpensive. But they don’t come in the color combination we favor for outside decorating (red/green/warm white) and idiot possums ate the lights last year and the year before so we didn’t bother with them this year.

The lights in question are by Philips and they’re standard mini-lights of the non-LED variety. This website says that they’re “mini” light bulbs and they’re 1/4 inch in diameter which seems correct.

However, the length (each are 1.5" from where the socket base meets the wire to the tip of the bulb) surely makes a difference and don’t the bulbs need some air flow to keep from burning out? The latter sure seemed to be an issue in my car until I left off the cap for the rear lights’ compartment.

So, what diameter do you recommend for the tubing? I’ll buy several yards of it and cut it to suit the length of the light strings so how long isn’t an issue.

First - get some tubing of the kind you are planning to use. Can you shrink it?

If so, get a large enough diameter that initial fit won’t matter, then insert lamps and shrink.

If you can’t shrink the stuff, either find some that will shrink or come up with something that splits open and re-seals.

Trying to string those lights into a 1/2" ID tube is not going to work (my guess).

The tubing is going to have to be pretty big since you’re going to have to fit one of the plug ends through it. Unless you’re going to snip them then re-crimp the ends back on.
Heat’s not an issue since the bulbs are in their own vacuum anyway and the heat they produce is so small it won’t melt anything.