SSP. The copper masking tape. To increase the coverage, you should fully pack the capacitor and connect a wire to GND (soldering a wire from copper shield to GND).
Copper tape can be found at several stores in Ap Liu street. Strangely, I think the well known ones (華輝,永盛) don't stock them anymore. Try those not so famous stores. The last time I went to Ap Liu street, I can only find 2 stores selling them [sorry, I forgot their names] .... but I have visited more than 6 of those electronics stores.