You’ve got plenty of choices, and each works a bit differently:

• Greaseproof paper cups – disposable, easy release, and often available in fun prints. Many are oven safe, and some note microwave use.
• Aluminum foil cups – sturdy shape, great for transport; some include clear lids. They’re typically oven safe and may list freezer or freezer-to-oven use.
• Reusable silicone cups – flexible and non-stick; many are oven, microwave, freezer, and dishwasher friendly (check the listing).

Review each product description for temperature limits and whether a muffin pan is recommended. Choosing between paper, foil, or silicone comes down to cleanup preference, how you’ll serve, and how much support you want during baking.

Square liners are offered in multiple sizes, so you can match your recipe and serving style:

• Mini – bite-size portions; many list sides around 1.5 inches.
• Medium/standard – everyday cupcakes; you’ll see options around ~2.75-inch sides or ~4–5 oz capacity.
• Larger dessert cups – deeper, box-style cups (often with lids), sometimes listed around ~10 oz.

Listings may use side length or fluid ounces, so it helps to check both. Bigger cups usually need more batter and a slightly longer bake. If you’re matching to a pan, measure the well size and compare to the dimensions on the product page to get a snug, tidy fit.

It’s straightforward with square liners or molds:

1. Set up: Use free-standing paper/foil cups on a rimmed baking sheet, or place liners in a square muffin pan or inside silicone cups for support.
2. Fill: Add batter to about 1/2–2/3 full to prevent overflow.
3. Bake: Use your recipe’s time and temperature as a guide; thicker, deeper cups may need a few extra minutes.
4. Cool: Let cupcakes set before lifting or adding lids.

Check the product listing for temperature limits and any pan requirements. Keeping cups close together helps them hold crisp edges. Results can vary with batter thickness and cup size, so start checking for doneness a bit early.

You can fold simple liners from oven-safe parchment if you’re in a pinch:

1. Cut parchment into squares (larger squares make deeper cups).
2. Fold up the four sides to form a shallow box and crease the corners.
3. Place the parchment boxes into a square muffin pan or nest them snugly together on a rimmed sheet to hold shape.
4. Fill halfway and bake, keeping an eye on edges.

Homemade liners may not stand as neatly as pre-formed cups, so close spacing helps. Always confirm your parchment is rated for oven use, and avoid wax paper. For a cleaner look and consistent results, pre-made square cups are a convenient alternative.

Support depends on the liner style you choose:

• Free‑standing paper or foil cups: Set them on a flat, heavy baking sheet; many note “no muffin pan needed.”
• Liner-only papers: Use a square muffin pan to keep sides upright.
• Silicone cups: Place directly on a sheet pan or inside a pan well for tidy rows.

Keeping cups close together helps maintain sharp corners. If you’re transporting, look for versions with lids. Always check the product page for pan requirements and maximum temperature guidance so you can choose the setup that fits your recipe and kitchen gear.