DSLR means Digital Single-Lens Reflex camera and basically refers to most of the latest digital cameras we’re using. A DSLR pinhole camera is the use of a DSLR without a lens but a tiny aperture.
In order to do that, you have to get a lens cap and drill a hole into it. For the DSLR pinhole to be working, the hole has to be the smallest as possible, however using standard drill bits you cannot achieve a sub-millimeter hole so I you can drill a big hole of 1 or 2 centimeters and on the top of it put an aluminium sheet and create a hole using a needle. The smallest the hole is, the more in-focus the photography will appear.
Here I put tape all around to avoid that the aluminum sheet to tear apart.
Using such a tiny hole will create an infinite depth of field, making all the elements, from the background and the foreground to appear at the same focus. However, as the hole is homemade using a needle and not sub-millimeter precise, the photo appears out of focus. You can get the precise dimension of the hole you need according the specifics of your camera using a dedicated formula that you can found on multiple online blogs.