Also, how long is your investment horizon? Is it really that important to you to project out to 30 years or is 3λ years sufficient along with a terminal value that represents the expected NPV beyond 5 years? Usually this latter approach works best and looks the most credible to potential investors. There are numerous ways to calculate terminal value including multiples, current market values projected forward, and round guesstimates. Obviously these decisions are affected by your personal preference and the type of investment for which you're calculating present value.
When you need durability _ Key card envelopes can be made in Tyvek as well as paper. Tyvek is tear_proof and water_resistant, and is an excellent choice when you need the envelope to be durable. If the card is something a person will hold onto for a long time, Tyvek is a better choice than paper. Key cards may only be used for a few days, but ID cards, ATM cards, and other cards that are distributed in envelopes might do better in Tyvek. A more durable envelope means the instructions for use will not fade or be lost when a paper envelope tears.