Gelatin-based hydrogels are simple and easy to make on your own. I have synthesized methacrylated gelatin (chemical modification) and gelatin-based thin films (crosslinkers used). There are tonnes of research articles that are focused on creating these gelatin-based hydrogels. But if you don't want to go through the process of making your own, there are also a lot of companies that sell commercial GelMA for research.

Having said that, here are some pointers to consider when working with GelMA. Mechanical properties of hydrogels can affect how your cells behave, so ensure you read literature to find out details on what percentage of GelMA would be ideal for your experiments, what percentage of methacrylation the components have (higher the methacrylation amount means higher crosslinking and stiffer gels). I focused more on GelMA here but similar principles apply for most of them. This is a very broad topic so you can choose what would serve ideal for your experiments based on your study. For my research, I encapsulated valve interstitial cells within GelMA. I wanted to study a coculture effect but couldn't get to that point during my PhD.

They are also biocompatible and biodegradable, other than comparatively stable and easy to prepare!