First of all: if you really want precision. I mean precision that one picture matches the other "pixel-perfect". I have to disappoint you because this is nearly impossible. However there are solutions that bring you close:

Solution 1: use a Template

This is very fast and produces very accurate positioning. The drawback is that you first need to "construct" a template and it is therefore only valuable if you have a series of similar objects.

Prerequisites:

• Put your camera on a heavy tripod or fixed position.
• create a template where your objects fit. This can be done from wood, cardboard or even paper. You could also use multiple different templates that fit the objects in different ways (frontside, backside, upside-down etc...) but all at the correct position.

Working steps

1. place the template
2. align the object with the template
3. remove the template
4. shoot the photo

Solution 2: Projector

This is the "electronic evolution" of the first solution. LED projectors have become cheap nowadays. It does not need to be a high quality projector - any cheap $100 LED or LCD projector will do. Smaller size can be an advantage.

With a projector, there are multiple possibilities to help you positioning your objects.

• as in solution 1, use a tripod for your camera
• mount the projector. I see three possibilities:
  1. mount the projector approximately above the camera onto the ceiling
  2. mount the projector next to the camera onto the same tripod
  3. use another tripod for the projector

Grid method:

1. project an image with a grid (like this) onto your object table
2. place and align the object along the grid
3. switch off the projector
4. shoot the photo

Picture method:

1. place the object onto the table
2. shoot a photo (but leave it in the position where it is)
3. project the image you just shot with the projector onto the object itself
4. remove the object and place and align the new object on the table
5. switch off the projector
6. shoot the next photo

Remark:

Since switching the projector on and off in short time can seriously reduce the lamp lifetime, you are probably better off just putting a cap onto the lens of the projector for the shoot. If you are taking photos with a flashlight, you probably do not need to care. (flashlight is much more bright than the projector).