Hi
If you want DIY All you need is some Tread All and a grinder and a hack saw
all available at Home Depot 3/8" Thread All will cost you about $4
cut them 2-2 1/2" long and grind one end to a sharp point now all you have to do is double nut the other end and paint them black If you dont want to do that and can live with small spikes Arrow Tips work very well
Available at a sports store for about $5 There all cheap but with a little effort just as effective as the $80 manufactured ones
Hope this helps