Easiest and cheapest way to get a good sounding call is to take an old coffee can and drill a small hole right in the center of the bottom. Put a piece of string about 2' longor old shoe lace through it and tie a large knot in the end so it can't be pulled through the hole. Wet the string and hold the can with one hand and slowly pull the string sliding your fingers down it. The coffee can acts like a megaphone and the sounds of the string will sound just like the wail and moan of a cow. I hate to tote one of those around and can simulate a cow or bull cow just by using my mouth. They have good hearing like a turkey and can hear it at a long distance. Be careful fooling around with moose calls particularly during the rut. They will come to almost anything that sounds like the real thing and are often pretty persistent. Both bulls and cows are big animals and even a calf is too large to deal with unless you intend to shoot it. A few years ago while deer hunting in northern NH I was coming out of the big woods just before dark and saw a calf looking at me from a ridge in a stand of hardwoods. I was about a mile from the truck and figured I would fool around with it and let out a couple of cow moans. Suddenly the calf started to bawl and started down the ridge right for me. I just looked as my safe distance of a couple of hundred yards melted away to about30 feet and the calf was bawling all the time. The thing stood taller than I was and looked about the size of a small horse and was too close for comfort. I didn't want to shoot it since it wasn't moose season but it was scaring the crap out of me. I didn't want to take my eyes off it and blindly reached down to find a stick on the logging road. I kept feeling some and was yelling at it but when I tried to throw the sticks they were all rotted and broke in my hand when I tried to throw them. By now it was about 10 feet from me, still bawling like crazy and had a really wild look in its eyes. I finally got a decent stick and hit it over the back and that stopped it from closing on me. I slowly backed away and it just stood there still bawling. When I got about 100 yds away I quietly turned around and started to walk very quickly back down the logging road to the truck. I could still hear it bawling when I got about a quarter mile from it. By now it was dark and I really felt uneasy and continued to check my back track. I moose season was over and I figured it was probably an orphan calf who was still looking for its mother. Since then I see moose and always go the other way.