The AMA and Medicare already factor essential medical supplies into a code's values on the provider fee schedule. If you're doing a procedure in the office that requires tools, surgical trays, or other supplies, the reasonable expectation is that you will be using equipment and the pricing for the procedure accounts for those costs. The purpose of the site of service differential in the Medicare fee schedule is to include these supplies and services. That's why you get paid more for the same procedure done in the office versus a facility.
You can use 99070 for separately billable supplies in your office. A better choice would be to use HCPCS Level II codes, however, because they describe the supply in much more detail and payers link them to a specific reimbursement. If you use 99070 you will need to provide a description of the supply and possibly a copy of the invoice from your supplier for pricing.
Medicare does not pay separately for trays and bundles them into the payment for the surgical code, such as laceration repair. The payment for the surgical code includes the practice expense associated with the tray.