to do some home improvement activities, D.I.Y., to tinker away at, to fiddle with 
[verb]
[knut-se-len, knut-sel-de, ge-knut-seld]

There’s not really an exact equivalent in English for "knutselen". It varies from a handyman doing some home improvement, Do It Yourself chores, or children fiddling with paper, scissor and crayons…

Examples:
– "Nina heeft een mooie collage geknutseld op school." 
("Nina has made a beautiful collage at school.")

– "Waar is Frank?" – "Hij is aan het knutselen in het tuinhuisje."
("Where is Frank?" – "He’s doing some home improvement in the garden house.")

– "Theo heeft het hele weekend besteed aan het knutselen aan zijn fiets." 
("Theo has spent the entire weekend on fiddling with his bike.")

Related words:
– Knippen: to cut, to use a scissor [verb] [knipte, geknipt].
– Plakken: to paste, to stick [verb] [plakte, geplakt].
– Kleuren: to colour [verb] [kleurde, gekleurd].
– Prutser: screw up <person> [noun] [de prutser, de prutsers].

Example:
– "Frank is een totale prutser."
("Frank is a total screw up.")

– Prutsen: to blunder, to be messing things up [verb] [prutste, geprutst].
– Verprutsen: to mess up [verb] [verprutste, verprutst].

stroke of a clock
[noun]
[de klok-slag, de klok-sla-gen]

"Klokslag" is composed of "klok" and "slag", which respectively translate to "clock" and "strike/stroke/blow. "Klokslag" is therefore the stroke of a clock.

You will encounter "klokslag" mostly though in the idiom "klokslag [t] uur" or "klokslag half [t]", where t can be any hour of the day. It is best translated with "at exactly [t] o’clock".

The English idiom "at the stroke of midnight" cannot be literally translated with "klokslag middernacht". This would be "precies om middernacht".

Examples:
– "Dat is gek, het is nu drie uur, en ik hoor vier klokslagen…" 
("That’s funny, it’s three o’clock now, and I hear four strokes now…")

– "Om klokslag zes uur zal een zwarte auto het geld oppikken. Volg deze niet." 
("At exactly six o’clock a black car will pick up the money. Do not follow.")

– "Precies om middernacht verandert Frank in een kikker." 
("At the stroke of midnight, Frank will change into a frog.")

Expressions:
– "Haastige spoed is zelden goed": haste makes waste.

Related words:
– Horloge: watch [noun] [het horloge, de horloges].
– Wijzer: pointer [noun] [de wijzer, de wijzers].

Example:
– "Als de grote en de kleine wijzer samenvallen, is het twaalf uur."
("If the hour and the minute pointer are aligned, it’s twelve o’clock.")

– Klok: clock [noun] [de klok, de klokken].
– Slag: strike, blow [noun] [de slag, de slagen].