I would make venison stock the same way I make beef stock. Look up recipes that first roast the bones and veggies(carrot, celery, and onion) with tomato paste brushed on them. Then I just throw all of it in my crock pot with lots of herbs, garlic, salt and pepper, and filtered water and let in cook. I usually start mine on high, and after about 8 hours I'll turn it to low and let it simmer for a full day total. This is how we made stock in culinary school and it has always turned out great. I'm sorry it's not more specific I don't use a recipe. That's why I recommend looking up a recipe online, it shouldn't be to hard to find. Also, I use a crock pot just because I have a gas stove and I feel for how long I have to cook a stock it's the safest and cheaper then simmering it all that time on a gas stove. I use a similar formula for all stocks(chicken, lamb, duck, ect.) and they turn out great.