No, this is not SPAM as the subject line might lead one to believe.
;-)

I have seen lots of wing tape. Many of the advertisements are for very
thin and flexible tape which conforms to the curves of the wing.
However, the cost can be prohibitive, especially if you assemble often.

A friend of mine (very high time & competitive pilot) uses 3M
electrical tape. We got to talking about it and we agreed that this
high quality tape is very flexible, has good temperature properties and
not very expensive. Easy to find also.

The only issue then was the thickness. Wouldn't the edge of the think
tape affect performance? The friend pointed out (correctly) that the
tape runs perpenticular to the span of the wing and thus the tape's
edge is parallel to the air flow. Thus no performance issues.

Any thoughts? What about with bug whippers?

Enjoy, John

PS There is one issue with 1/2" wide electrical tape - whether it is
wide enough to bridge the gap. It all depends, I suppose, on the fit
and finish of your glider.