Glass suction cup extender m4 thread

PETG with this. Metric drill and tap set needed. it looks rough because it was printed at .68 with a 1mm nozzle but it could equally be any layer height. Drill out to 3.2 or 3.5mm as appropriate. Tap with an M4 tap from the top end to leave the business end thread in a good state. Equally if requiring the good part of the thread to be at the top tap it from the other end. M4 is supposed to be 3.2mm drill but I drilled these with 3.5mm which works adequately. I used this to fit my van window insulation as the fixing thickness is more than the standard fitting allows. Also the diameter of the standard fixings was too small. It works perfectly. The original suction cups failed in the hot sun and were frankly "not very good" ever even when new. The set of suction cups were purchased from Amazon and are immediately better and rated from -40 to plus 80.