I did a 5 day trip in Amsterdam, which I think it was excessive. 3 days would have been perfect.
Going by Ryanair, you fly in to Eindhoven airport. Afterwards, take a 3.50 euro bus (20 min) to the Eindhoven train station. Then take a train to Amsterdam Central (18.70 euro, 1.5 hours). So it can get pretty expensive.
You can spend the last day walking around some sights in Amsterdam, like the Heineken Experience, Van Gogh Museum, Anne Frank House, etc. They cost about 5-15 euros per visit.
Transport in Amsterdam can be quite expensive. Renting a bike costs like 7.50 euros a day. A bus ride costs 2.80. A day transport bus covering metro, bus, etc. costs 7.50 euros a day and gets cheaper if you buy multiple days. You buy this from the Tourist Information centre near Amsterdam Central.
Coffeeshops
In Amsterdam, many drugs are legalized. So there are opportunities to try some things that you can definitely not do in Singapore. I tried pot brownies, smoking weed and truffles (milder magic mushrooms as mushrooms are banned now). One piece of pot brownie costs 6-7 euros, a stick of weed (or a joint) costs 3 euros, and truffles cost 20 euros a box.
IMO, skip pot brownies as I think that they are a waste of money. I ate 1.5 pieces myself and nothing happened. Smoking weed isn't a pleasant feeling if you are not a smoker, and it requires some technique to smoke correctly. I bought the mildest truffle, which is a mistake, as I did not feel much after eating half a box. And they taste horrible, simply disgusting. If I were to try again, I would skip smoking weed as well, and buy stronger truffles to try. But it can be just that my body is resistant to drugs, so don't blame me if you go wild after eating 1 pot brownie. Here's what they look like. Truffles is the one that look like goat shit.
Looks like goat dung
