Went to see a supplier of rims the other week. Noted that the tubeless tape they were using was blue Scotch 8898 which can be found online in 18 and 25mm widths but only in packs of 12 upwards. 60yds for about £6 a roll in 12 or 18s, approx.

Just posting in case anyone finds it in smaller qty or wants to go in on a bulk buy as a try-out. I’ve not used it but it has a high-strength spec and was being promoted for use with sealant.