The obvious place to look first is the company's recent SEC filings. 

In particular, I focused on AMAT's most recent quarterly report (10-Q). This proved to be immensely useful in understanding the company (unsurprisingly).

Notably, the notes to financial statements actually had extremely useful information, such as detailed breakdowns of their long-term debts, as well as information on stock issuances and buybacks.

Other than the 10-Q, external data sources like Yahoo Finance, S&P, YCharts, Bond Insider, etc were also beneficial for various calculations.

Using a spreadsheet, we are able to efficiently cruch calculations to find the company's current capital structure, as well as to find their optimal capital structure.

The optimal capital structure is the ideal mix of funding (debt & equity) that minimizes their cost of capital (WACC) and maximizes the value of the firm. This was calculated to be approximately 25%.

Concepts used at various points in the calculation include:

• Hamada Equation (levered & unlevered beta)

• CAPM and WACC formulas

• PV of bonds (to find market value of debt)

• Default risk (associated with increased leverage)

• EBIT and EPS 

Ultimately, the numbers need to be understandable to anyone we present them to. For this, visual aids like graphs are crucial.

Using a multitude of different graphs, we are able to effectively present the calculations to an audience, maintaining engagement and ensuring their understanding. This is the aim of any presentation.