The 7,910,474 shares of Class A common stock registered for resale pursuant to this prospectus consist of: (i) 4,666,667shares of Class A common stock (the “Private Placement Shares”) issued to the Selling Shareholders pursuant to the SecuritiesPurchase Agreement dated June 30, 2026 (the “SPA”); and (ii) 3,243,807 shares of Class A common stock (the “Pre-Funded WarrantShares”) issuable upon the exercise of certain pre-funded warrants issued to the Selling Shareholders on July 2, 2026 (the “Pre-FundedWarrants”). We are not selling any securities under this prospectus, and will not receive any of the proceeds from the resale or otherdisposition of the shares of our Class A common stock by the Selling Shareholders. We will bear all costs, fees and expenses incidentto our obligation to register the offer and sale of the shares of Class A common stock. The Selling Shareholders will bear allcommissions and discounts, if any, attributable to its sale of shares of Class A common stock. See the section titled “SellingShareholders” on page 74 for additional information regarding the Selling Shareholders. For more information on possible methods ofoffer and sale by the Selling Shareholders, please see the section entitled “Plan of Distribution” beginning on page 76 of thisprospectus. We have two classes of common stock: Class A common stock and Class B common stock. The rights of the holders of ClassA common stock and Class B common stock are identical, except with respect to voting, conversion and transfer rights. Each share ofClass A common stock is entitled to one vote. Each share of Class B common stock is entitled to 15 votes and may be converted at anytime into one share of Class A common stock. Each share of Class B common stock will automatically convert into one share of ClassA common stock upon any sale or transfer thereof, subject to certain exceptions, such as certain transfers effected for estate planningor charitable purposes. Shares of Class B common stock may only be issued to and held by William A. Mobley, Jr., our founder, ChiefExecutive Officer and Chairman, and certain permitted entities owned and controlled by Mr. Mobley. See “Description of CapitalStock” for more information. We are a “controlled company” under the Nasdaq Global Market (“Nasdaq”) corporate governance standards because morethan 50% of the voting power of our common stock is held by William A. Mobley, Jr. As a “controlled company,” we are permitted to,and have, elected not to comply with certain Nasdaq corporate governance standards, including majority “independent director”requirements and certain requirements relating to independent compensation and nominating committees. Accordingly, you will nothave the same protections afforded to shareholders of companies that are subject to all of the corporate governance requirements ofNasdaq. Our Class A common stock is listed on the Nasdaq Global Market under the symbol “CAST”. On July 22, 2026, the lastreported sale price of our Class A common stock on the Nasdaq Global Market was $2.30 per share. We are an “emerging growth company” as defined under the federal securities laws and, as such, have elected tocomply with certain reduced reporting requirements for this prospectus and other filings with the Securities and ExchangeCommission. For more information, see“Prospectus Summary—Emerging Growth Company Status.” Investing in our securities involves a high degree of risk. You should carefully consider the risk factors beginning onpage 9 of this prospectus before purchasing shares of our Class A common stock. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminaloffense. The date of this prospectus is July 23, 2026. TABLE OF CONTENTS PagePROSPECTUS SUMMARY1RISK FACTORS9CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS23USE OF PROCEEDS23DIVIDEND POLICY24CAPITALIZATION24SELECTED HISTORICAL FINANCIAL AND OPERATING DATA25MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OFOPERATIONS26DESCRIPTION OF THE BUSINESS43DIRECTORS AND EXECUTIVE OFFICERS54EXECUTIVE COMPENSATION58CERTAIN RELATIONSHIPS AND RELATED-PARTY TRANSACTIONS65SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT67DESCRIPTION OF CAPITAL STOCK69PRIVATE PLACEMENT OF SHARES OF CLASS A COMMON STOCK AND WARRANTS72SELLING SHAREHOLDERS74PLAN OF DISTRIBUTION76DISCLOSURE OF COMMISSION POSITION ON INDEMNIFICATION FOR SECURITIESACTLIABILITIES77LEGAL MATTERS78EXPERTS78WHERE YOU CAN FIND MORE INFORMATION78INDEX TO FINANCIAL STATEMENTSF-1 Neither we nor the Selling Shareholders have authorized anyone to provide you with information that is different from thatcontained in this prospectus or in any free writing prospectus we may authorize to be delivered or made available to you. When youmake a decision about whether to purc