If your kid wants a Roblox party and there aren't enough Roblox merchandise to give you options, you can always DIY some items. For one, you can purchase and download printables from various sellers on Etsy. There are printables for almost everything you'll need: from invitations to goodie bags, to cake and cupcake toppers, to banners and buntings, to stickers, to chocolate bar wrappers and chip bags, and activity sheets. Another option would be to buy or print your own Roblox stickers and use them to "brand" generic party supplies like party cups, banners, and loot bags.