Here is what I do at home, when the weather is bad. I take a fire brick and putt balls to one of the smaller ends from about 6'. I use enough stroke that after hitting the brick the ball returns to me. The small end of the brick measures about 3" wide, which is much smaller than an actual golf hole.

By hitting the small end of the brick, I am working on accuracy. By hitting the ball hard enough for it return the 6' back to me, I am working on my putting stroke speed. My carpet is some what slow to putt on, but by trial and error, I have found the 6' return distance works well for me once I am on a level, green with a putt of 10-12 feet. This distance also gives me some what of reference point for down hill, and up hill putts. Putting "feel" if you wish.

Remember, all putts are straight. Obviously all putts are not always straight at the hole. Those putts not straight at the hole, are straight to a predetermined spot due to the contours of the green, but are still straight putts none the less... GJS