You can find many free baseball cap patterns online, or you can purchase a baseball cap pattern from a craft supply store. Choose a pattern in the style and size that you want, and then cut out the paper pattern pieces.  Make sure to use a sharp pair of scissors to cut out the pattern pieces. Cut along the lines on the pattern pieces for the size you want the hat to be.
++++++++++
One-sentence summary -- Find or purchase a hat pattern.

Article: To set up an eBay account, click on the blue “register” hyperlink in the top left corner of the homepage. You’ll be asked to provide basic personal information, a method of payment for your seller’s fees, and a username. Think of your username as the company name of your online store. Make it a personal brand that is appealing and catchy without sounding too obscure or awkward. You’ll receive payments from any clothes you sell through PayPal. A verified account is easy to set up, allows to you sell internationally, and gives you more credibility on eBay. You’ll find a link to PayPal setup on your eBay account page. To begin, click on the “Sell” link on the top left-hand side of the eBay homepage. After choosing “Create a listing,” you’ll be asked to type in a description of the item. Follow the example provided, listing at least of few characteristics of the item, including gender, size, color, and style. A category will then be suggested for you, and if it seems accurate, click on “Create Listing.” For example, a search for “women’s gray LL Bean capri pants size 10" will recommend the category of "Pants." Include basic elements such as brand name, style, color, and material. The more descriptive your title, the more often the item will show up in shoppers' search results. For example, an appropriate title for a pair of jeans is something like, "Ralph Lauren Polo Jeans Black Classic Boot Cut Size 8." Be as descriptive as possible, including the brand name, material, size, color, and any pattern or embellishments. Use adjectives such as “dark” and “light” for colors, since the photo won’t appear the same on all screens. For women’s dresses give waist size and dress length, and for men’s shirts give armpit-to-armpit length, plus sleeve length.  For example, a good description of a vintage blouse would be, "Vintage 70's Pat Argenti sheer ruffle front blouse. Small black buttons in back, faux button front. No size tag so please check measurements for fitting. Measures unstretched  approximately:  40" (102cm) bust, 40" waist, 23" (58cm) shoulder to hemline. Dark green velvet ribbon detailing. Please note ribbon coming apart near the neck, also separating near the underarm & bust seams." Give all measurements in both inches and centimeters for the convenience of international shoppers. Other helpful measurements include bust/chest, waist, hips, inseam, pant length, and bell width (for skirts or dresses). You have the option of selling the item at a price that you set, or putting it up for bid along with the option of a fixed-price sale (“Buy it Now”). If you’re concerned about your auction item selling at a really low price, you can set a reserve price under which it can’t be sold. Otherwise, for less valuable items, setting a low starting bid at $1 or lower can attract a high volume of bargain hunters. The greater the number of bidders, the better the chance for bidding competition that elevates selling prices. On the "Create Your Listing" page, in the section titled "Bring your item to life with pictures, click on "Add Pictures." You can add one photo for free, but additional shots will cost a little extra. It's worth paying this extra price, especially for the more valuable items, to add several pictures for the the customers' convenience. You can make three shipping price options available to potential customers: free shipping, flat fee shipping, and calculated cost shipping. Offer at least one other method besides free shipping in case the customer needs expedited shipping.  For flat fee shipping, you set the shipping price when listing the item, based its packed weight. Use eBay’s shipping cost calculator to help estimate a cost for your item.  With calculated cost shipping, the shipping cost will be calculated for your customers at check out, based on your zip code, the customer’s zip code, and the weight of the packed item. You’ll be given the option to choose mail carriers and shipping speeds to offer to potential buyers. Make as many shipping methods available as you’re willing to accommodate, but try at least to offer several expedited shipping options, since some customers might decide not to buy your item if they can’t get it promptly. Strongly consider offering free shipping: it’s an incentive to buyers, you’ll get an automatic 5-star seller rating for shipping, and you’ll show up higher on the list of shoppers’ searches for your items.
Question: What is a summary of what this article is about?
Register for a seller account. Register for a verified PayPal account. Choose an appropriate category for each item. Write an informative title. Describe the item in detail. Decide on a pricing format. Upload your photos. Set a shipping price. Offer several shipping options.