CRA's definition of Office Expenses for a rental property is:

You can deduct the cost of office expenses. These include small items such as pens, pencils, paper clips, stationery, and stamps.

If you can prove that your printer and shredder are used exclusively for your rental operation, you might be able to claim them as a deduction. However, CRA would likely disallow the claim if they feel it is "unreasonable".