Hornbeams (Carpinus betulus) are becoming one of my favorite species for bonsai cultivation. They grow fast, respond well to different pruning techniques and you can easily reduce their leaf size. I also think they make great bonsai for beginners! Only repotting them can be a bit tricky sometimes, as I learned the hard way.
Air layering is a relatively fast and easy method of propagation you can use to create bonsai from larger trees and shrubs. In essence, air layering is way to grow roots on a part of the plant that otherwise wouldn't grow roots, like a branch or in the middle of the trunk. This technique is usually carried out in mid to late spring.
Elms push out lots of new shoots every spring. If you don't keep an eye on it, the canopy fills up fast, even in places where you don't want any new growth. I try to remove any unwanted shoots as soon as possible, as these can cause swelling and inverse taper.
I've grown this field elm (Ulmus minor) for 3 years from cuttings. The trunks were bound together with aluminum wire in the first year after they rooted (below) and now they've already fused together quite nicely.
I grew these dawn redwoods (Metasequoia glyptostroboides) from seed about 3 years ago. In the winter of 2019 I cold stratified them in the fridge for a month and then randomly sowed them in a shallow container. This method of creating forest planting can give surprising results, as you don't know what the composition will look like in the end.