It happened to me that I very urgently needed an element holder for a VHF antenna. I used an emergency solution, a cork from coca cola, which I drilled twice from the side and twice from the bottom. For the element, the hole must be very tight. Basically, we press the element there by hand. The bottom two holes are for attaching the element to the supporting rod. For long-term use, fill the plug with epoxy. I recommend making a simple fixture for drilling holes.
Dušan OM3CVV