My favorite battery, the adapter :). It is easy to make, easy to maintain, easy to change the cells. True, you will need fresh cells every time (well, actually I change the cells once every 6 months or once per year, depends on how much I use the cameras). As long as you use the right cells, and you take care when you insert the thingy in the battery chamber of your camera, all is well, or should be.
The sleeve is easy to procure: I usually open old PX27 batteries, depleted, and harvest as follows: the bottom plate, the top nipple, any metallic separators (if any) and the plastic tube. I discard the cells (careful, you'll need to dispose of these in the right manner and responsible), and the metallic jacket, which is the outside layer of the battery. Clean the bottom plate and the top nipple, as they may have some remnants of lead, from the previous soldering. Make sure they're not bent, and that the plastic sleeve is not cracked. Put fresh batteries inside; sometimes you'll need to fit the separator, or the bottom and top thingies. This is needed because sometimes the distance between the contact plates inside the battery camera may need to be corrected in such a way. Very rare, but I have met with such situations.
I have been in certain situations, while traveling, when the plastic tube cracked, and I used a small piece of cardboard, cut and rolled in the shape of a small tube. The cells went inside and all was well. Mind, you'll need to make sure the cardboard tube is changed with a plastic sleeve as soon as possible, because it draws humidity from the air; not a good thing to have inside your battery chamber.
You will notice that the cells used are not all of the same type: there are 3 x AG12/LR43 and 1 x AG13/LR44. This is because the length between the contacts of the camera need to be covered completely, and if you employ the use of 4 x AG12/LR43 cells, you will be short of some 1.2 - 1.4mm or thereabouts. Obviously, you may use the separators or plates you have collected from the battery you destroyed, and the adapter will work all right. However, I have found that using a pack made up by 3 x AG12/LR43 and 1 x AG13/LR44 cells, it works wonderful, and I do not need to down the voltage from 6V (4 x 1,5V) to 5.6V. I have not noticed any difference in shutter operation in both of the voltage situations. The separators of metallic plates, if used, will down the voltage, but as I have said, no noticeable differences.