OTHER IDEAS
If you enjoy inventing new products, making incremental changes to existing products, making dramatic changes to existing products and generally doing product development, then you can go ahead and exploit another idea. Then follow the steps outlined above to get the product to market. You can have variations of the same product. For example, if you are making design changes for a toothbrush, or making a design for a new toothbrush, you can make one version for kids, another version for teenagers and another version for adults. In this way you will have three different versions for three different markets. Hence you will earn royalties from these three different versions.
Like I said before, you must be on the lookout for everyday problems that you can solve with a patented idea. You should also visit the supermarkets, the stores, the tool stores and the retail outlets to have a thorough look at all their products. By careful observation of these products, you will quickly spot a product that needs an incremental improvement and by all means go ahead and make the changes on paper. You do not have to stick to one product like the toothbrush ideas. You can try other products. On the internet you will see the variety of inventions Thomas Edison, George Westinghouse and Nikola Tesla explored, and they did not stick to just one idea or one product. They took a broad view of things and came up with a wide variety of products and improvements. You can do the same.
With you existing portfolios of products, you can aspire to make further improvements to them every two or three years, so they will be relevant for the ever changing market. Humans are always on the look out for new products. They always want to try something new in the form of a new product. On many occasions, they want to be a part of the trend, the hip, the glamour, the coolness and in the game. So you need to tap into this behaviour of humans, realise that they always want to use a new product and make the design improvement that they want and you know will sell.